Very small embryonic-like stem cells are involved in regeneration of mouse pancreas post-pancreatectomy
© Bhartiya et al.; licensee BioMed Central Ltd. 2014
Received: 19 June 2014
Accepted: 21 August 2014
Published: 2 September 2014
Despite numerous research efforts, mechanisms underlying regeneration of pancreas remains controversial. Views are divided whether stem cells are involved during pancreatic regeneration or it involves duplication of pre-existing islets or ductal cells or whether pancreatic islet numbers are fixed by birth or they renew throughout life. Pluripotent embryonic stem (ES) and induced pluripotent stem (iPS) cells have been used by several groups to regenerate diabetic mouse pancreas but the beneficial effects are short-lived. It has been suggested that cells obtained after directed differentiation of ES/iPS cells resemble fetal and not their adult counterparts; thus are functionally different and may be of little use to regenerate adult pancreas. A novel population of pluripotent very small embryonic-like stem cells (VSELs) exists in several adult body tissues in both mice and humans. VSELs have been reported in the mouse pancreas, and nuclear octamer-binding transcription factor 4 (OCT-4) positive, small-sized cells have also been detected in human pancreas. VSELs are mobilized into peripheral blood in streptozotocin treated diabetic mice and also in patients with pancreatic cancer. This study aimed to evaluate whether VSELs are involved during regeneration of adult mouse pancreas after partial pancreatectomy.
Mice were subjected to partial pancreatectomy wherein almost 70% of pancreas was surgically removed and residual pancreas was studied on Days 1, 3 and 5 post-surgery.
VSELs were detected in Hematoxylin and Eosin stained smears of pancreatic tissue as spherical, small sized cells with a large nucleus surrounded by a thin rim of cytoplasm and could be sorted as LIN-/CD45-/SCA-1+ cells by flow cytometry. Results reveal that although neutrophils with multi-lobed nuclei are mobilized into the pancreas on day 1 after pancreatectomy, by day 5 VSELs with spherical nuclei, high nucleo-cytoplasmic ratio and nuclear OCT-4 are mobilized into the residual pancreas. VSELs undergo differentiation and give rise to PDX-1 and OCT-4 positive progenitors which possibly regenerate both acinar cells and islets.
Results provide direct evidence supporting the presence of VSELs in adult mouse pancreas and their role during regeneration. VSELs are an interesting alternative to ES/iPS cells to regenerate a diabetic pancreas in future.
Despite decades of research, the mechanism underlying regeneration of adult pancreas remains controversial [1, 2]. Bouwens and colleagues concluded in their recent review that although the pancreas has long been known to have huge potential to regenerate, it is still not evident whether the pancreas houses stem cells for regeneration or not . No consensus exists as to whether regeneration occurs by duplication of pre-existing cells or pancreatic ductal stem cells are involved. Wang and colleagues provided evidence via differential BrdU uptake by the beta cells and ductal epithelium in the pancreas after pancreatectomy that beta cells do not form from pre-existing islets . Xu and colleagues provided further evidence against the concept of re-duplication of pre-existing islets by showing the existence of novel multipotent progenitors in mouse pancreas that may be responsible for regeneration of beta islet cells , and their findings have huge translational value to treat diabetes. Understanding the underlying mechanisms of pancreatic regeneration post pancreatectomy becomes crucial and an urgent quest exists to find adult pancreas stem cells. This kind of understanding will help to tackle the increasing magnitude of diabetes that has become a global epidemic. At present, there are approximately 346 million adult diabetic patients worldwide. By 2030 the number of diabetic patients is expected to reach 4 billion, and China and India are leading diabetes prevalence in the world .
Stem cells have captured the fascination of one and all because of their possible applications in regenerative medicine. The stem cells are broadly classified as pluripotent (embryonic stem (ES), induced pluripotent stem (iPS)) cells and tissue-specific adult multipotent or unipotent stem cells. Ratajczak’s group proposed the existence of an entirely novel group of pluripotent stem cells in adult body organs  termed very small embryonic-like stem cells (VSELs), and their very existence in adult body organs makes redundant the need to grow other pluripotent stem cells (ES or iPS cells) in a Petri dish for regenerative medicine. VSELs (LIN–/CD45–/SCA-1+) are hypothesized to be derived from the late migrating primordial germ cells and deposited in various body organs during early embryonic development [8–10], are mobilized under disease conditions [11–16] and are hypothesized to be possible embryonic remnants responsible for various cancers in adult life . As expected from other pluripotent stem cells (ES and iPS cells), VSELs have the ability to self-renew and differentiate into three lineages in humans  as well as in mice . Unlike ES and iPS cells, however, VSELs do not divide rapidly in culture, do not complement blastocyst development and do not form teratoma on being injected in immunocompromised mice. This inability of VSELs is due to a novel epigenetic mechanism of imprint erasure on paternally imprinted differentially methylated regions (DMRs) (H19-Igf2, RasGRF1)  and as a result they remain relatively quiescent and most probably undergo asymmetric cell divisions compared with ES cells, which undergo rapid symmetric divisions in vitro. Besides maintaining normal homeostasis, VSELs have been implicated to play an important role in regeneration [20, 21]. We have reported them in cord blood, bone marrow and adult testis and ovary [22, 23]. We have further observed that VSELs survive chemotherapy in both mouse ovary and testis, in agreement with an earlier report that VSELs survive in mouse bone marrow after radiotherapy whereas the hematopoietic stem cells are destroyed , and can restore gonadal function when appropriate conditions are provided (DB, 2014). The main reason why these stem cells have remained elusive until now is their very small size, as a result of which they are easily and unknowingly discarded during processing. Here we provide morphological and additional evidence about their existence and homing ability into the mouse pancreas after pancreatectomy. Hopefully, observing nuclear OCT-4-positive VSELs in a morphological context in the blood vessels and their presence in the newly formed lobes of pancreas that regenerate by day 5 post pancreatectomy in mice along with progenitors which colocalize OCT-4 and pancreas duodenum homeobox-1 (PDX-1) by various technical approaches (immunolocalization, confocal microscopy and reverse transcription-polymerase chain reaction) will convince the scientific community about the existence and potential of pancreatic VSELs.
The study was approved by the Institute Animal Ethics Committee (IAEC/NIRRH 19/13) and was carried out using in-house bred Swiss mice in the experimental animal facility. Mice were housed in a temperature-controlled and humidity-controlled room on a 12-hour light/12-hour darkness cycle with free access to food and water. Swiss mice 8 to 10 weeks old were used for partial pancreatectomy as described earlier . Residual pancreas was harvested on days 1, 3 and 5 after surgery for histology, immunolocalization and RNA extraction. Pancreatic tissue was also appropriately processed to obtain cell suspensions for immunofluorescence and flow cytometry studies.
The pancreas was removed after partial pancreatectomy, formalin fixed, processed and embedded in paraffin using standard protocols. Then 5 μm thick sections of the embedded pancreatic tissue were prepared and stained with hematoxylin and eosin (H & E) to study the histo-architecture. The representative areas were photographed using a 90i microscope (Nikon, Tokyo, Japan).
Immunolocalization studies were carried out for OCT-4 (nuclear transcription factor reflecting a pluripotent state) and PDX-1 (nuclear transcription factor specific for pancreas development). Briefly, the paraffin sections were deparaffinized and hydrated and antigen retrieval was performed by boiling in saline sodium citrate buffer (pH 6) for 15 minutes. After cooling, the slides were washed with Tris buffer saline for 5 minutes followed by blocking with 10% serum and 1% bovine serum albumin in Tris buffer saline. Later the slides were incubated with primary antibody diluted with 1% bovine serum albumin in Tris buffer saline for 2 hours at room temperature (polyclonal OCT-4 antibody, 1:200 and polyclonal PDX-1, 1:500 antibody; both Abcam, Cambridge, UK). The detection was carried out using the anti-mouse Vecta ABC kit (Vector Laboratories, Burlingame, CA, USA) and diaminobenzidine (BioGenex, San Ramon, CA, USA). After counterstaining with hematoxylin, the slides were viewed under a microscope.
Reverse transcription-polymerase chain reaction studies
Primers used for reverse transcription-polymerase chain reaction studies
Product size (base pairs)
Preparation of pancreatic cell suspension for various studies
Histological changes post pancreatectomy
Pluripotent VSELs home into mouse pancreas during regeneration
Searching for VSELs in normal pancreas
We studied the presence of VSELs in normal mouse pancreas. H & E-stained smears showed the presence of VSELs characterized by their very small size, spherical shape, high nucleocytoplasmic ratio and intensely stained nuclei (Figure 5A,B,C). They could be easily distinguished from the bigger somatic cells with abundant cytoplasm and pale-stained nuclei. The VSELs studied and reported by our group in testis, ovary, cord blood and bone marrow, umbilical cord tissue show similar appearance after H & E staining [22, 23]. The cell suspension obtained after enzymatic digestion was also studied by flow cytometry for the presence of 2 to 5 μm VSELs that are LIN–/CD45–/SCA-1+, as described in the available literature . Briefly cells in the size range of 2-5 µm were gated according to the strategy shown in Figure 5. LIN negative population (P2) was gated from P1 population representing cells in the size range of 2-5 µm. Further CD45 negative cells (P4) were gated from P2. Finally SCA-1 positive cells (P7) were gated from P4. Experiments run in triplicate reveal that 0.6 ± 0.06% of pancreatic cell suspension comprises VSELs (Figure 5).
Pluripotent VSELs differentiate into PDX-1-positive progenitors that further give rise to both exocrine and endocrine cells
The present study establishes that pancreatic regeneration has a stem cell basis and that neogenesis of islets does occur, contradicting available literature. Xiao and colleagues found no evidence of beta-cell neogenesis in adult pancreas . Unequivocal evidence for the presence of pluripotent VSELs in adult pancreas and their involvement in regeneration post pancreatectomy is provided. VSELs exist in small numbers in normal pancreas (0.6 ± 0.06% of pancreatic cells), but after partial pancreatectomy large numbers are mobilized into the pancreas where they are involved in regeneration. VSELs 2 to 5 μm that are LIN–/CD45–/SCA-1+ and express Oct-4 and Sox2 differentiate into PDX-1-positive progenitors that further give rise to both acinar and islet cells.
Increased trafficking of VSELs and mesenchymal stem cells was reported in the peripheral blood of patients with pancreatic cancer compared with healthy controls . Scarlett and colleagues earlier suggested that bone marrow-derived stem cells may be involved during regeneration of mouse pancreas . Two groups have also described earlier the presence of two distinct populations of cells including small and slightly bigger OCT-4-positive cells in human pancreas [31, 32]. Zhao and colleagues detected stem cell markers Oct-4, Sox 2 and CD34 in islet-enriched fractions of all 25 adult human pancreas samples, with no significant differences between endocrine and exocrine cell fractions . Immunohistochemical staining for OCT-4, SOX-2, CD133, CD34, CK19, insulin and nestin on human pancreas sections showed that the majority of OCT-4-positive cells were found in the walls of small ducts. Similar localizations were observed for SOX-2-positive cells. The majority of SOX-2-expressing cells were found to coexpress OCT-4, but not vice versa. The majority of OCT-4-positive cells had cytosolic staining, while a small number (approximately 1.6%) of cells showed nuclear OCT-4. White and colleagues found nuclear coexpression of pluripotent markers OCT-4/SOX2/NANOG in proliferative islet survivor cells and also in adult human pancreas as well as islet fraction samples . Various techniques such as confocal microscopy, flow cytometry and also western blotting were used to confirm the results. These cells were very small in size (1.5 to 3 μm), resembling VSELs. Expression of OCT-4 in human pancreas-derived primary cell cultures has also been reported [33, 34]. Several groups have thus suggested the presence of OCT-4-positive stem cells in mouse and human pancreas and the results of the present study are in agreement with these earlier reports.
It is rather surprising that despite available reports reviewed above in humans as well as in mice, VSELs have evaded the biologists for so long during so many studies undertaken on pancreatic regeneration after pancreatectomy. Recently, the group of Irvine Weissman, a leading stem cell biologist from Stanford University, created a controversy  when they denied the presence of VSELs in mouse bone marrow  in agreement with three earlier publications [37–39]. Ratajczak’s group enumerated various factors [12, 40, 41] that could have led to erroneous results by the Stanford group and others. During the present study, we knew what to look for in the pancreatic tissue sections (after pancreatectomy), having worked and published extensively on ovarian, testicular, cord blood and bone marrow VSELs for the last 5 years [22, 23]. Melton’s group used elegant lineage tracing studies to show that adult pancreatic islets are formed by re-duplication rather than stem cell differentiation, and also concluded on the power of the lineage tracing approach over histological snapshots to determine the origin of a cell type . But the histological snapshots in our study have provided novel information on pancreatic regeneration provided one knows what to look for! An alternative explanation to the observed results and conclusions made by Dor and colleagues  is possible based on the present study results and VSEL biology. A careful examination of their methods shows that five injections of tamoxifen were given (4 mg, intraperitoneal or subcutaneous twice a week) over a period of more than 15 days that resulted in nuclear translocation of CreER protein, allowing expression of human placental alkaline phosphatase in insulin-expressing cells as well as their progeny. But during this time of more than 2 weeks, VSELs (expected to also harbor the transgene) could also have differentiated into human placental alkaline phosphatase expressing beta cells. Results of present study clearly show that islets are newly formed in the new pancreatic lobes within 5 days (Figure 1J). Thus, rather than re-duplication of pre-existing islets to produce new beta cells (after 15 days of tamoxifen injections) during adult life and after pancreatectomy as concluded by Melton’s group, the new islets could also regenerate from pluripotent VSELs. The present study also highlights the importance of coelomic epithelium during regeneration. The acinar cells appear to differentiate along the coelomic epithelial layer covering the pancreas surface (Figure 1H,I). Li and colleagues reported that differentiation of embryonic pancreas in the presence of mesenchyme, but an absence of coelomic epithelium, led to decreased acinar tissue differentiation .
No study is complete in itself and rather provides newer avenues for further research. Studies are underway in our laboratory to understand why VSELs fail to regenerate the islets in a diabetic pancreas and whether these stem cells could be manipulated to cure diabetes. It has been earlier documented that pancreatectomy of STZ-treated pancreas results in regeneration and also restores the euglycemic state in mice [25, 26]. We have also found that STZ treatment does not affect VSELs as suggested by the expression of pluripotent transcripts in the pancreatic tissue (DB, unpublished data, 2014). Huang and colleagues have earlier reported mobilization of VSELs from the bone marrow that home into the STZ-treated mouse pancreas associated with a several-fold increase in pancreas-specific markers (110-fold increase in Nkx6.1, eightfold to 10 fold increase in Pdx-1 and Ptf-1), and also Sdf-1 (a chemokine involved in mobilization) mRNA was upregulated . Further, transplantation of EGFP+ bone marrow cells in STZ mice lowered blood glucose significantly but hyperglycemia reappeared after 84 days. The increased expression of pancreas specific transcripts in bone marrow observed by Huang and colleagues is not surprising, but rather speaks for the potential of VSELs. Being pluripotent by nature, VSELs have the ability to differentiate into any cell type, depending on the body’s requirements. Specific markers are expressed and reported in bone marrow and peripheral blood depending on the type of disease; for example, Nkx-1 and Pdx-1 are upregulated in response to pancreatic damage , germ cell-specific markers are expressed when gonadal function is compromised by treatment with busulphan in ovary  as well as in testis , and neural markers are elevated in the case of stroke . This potential of VSELs to differentiate into specific progenitors depending on their somatic microenvironment and the requirement of the body needs to be appreciated and further explored. Transplantation of beta cells or progenitors obtained after differentiation of ES cells has shown considerable promise , but the beneficial effect has remained short lived. Few groups also report an advantage of using mesenchymal cells to improve symptoms [49–51]. All of these varied attempts by the scientific community are not able to outsmart Mother Nature to cure diabetes and we need to pause and deliberate on various available options with an open mind.
Tabar and Studer have recently reviewed the advances and existing shortcomings of translating pluripotent ES and iPS cells to the clinic . They discuss the associated costs, regulatory requirements, scale-up, good manufacturing practice-compliant cultures and related genetic and epigenetic issues. Most importantly, they summarize that the functional status of differentiated cells obtained from pluripotent stem cells resembles their embryonic and fetal counterparts. But the main aim of regenerative medicine is to replace diseased cells in adults with healthy, fully functional cells. The few trials undertaken using human ES cell-derived pancreatic progenitors in mice show only short-term benefit. Against this background, VSELs are autologous, pluripotent stem cells present in adult organs and have no associated ethics, and the present study shows their potential to regenerate adult pancreas. We thus propose that an urgent need exists to develop strategies to manipulate VSELs within the body to our advantage rather than expanding and then differentiating stem cells in a dish. The presence of VSELs in very low numbers should not deter us because they give rise to progenitors that divide rapidly (clonal expansion) in large numbers.
To conclude, detection of VSELs in situ in normal adult pancreas and their involvement during regeneration in the present study offers a practical option for regenerative medicine by manipulating the endogenous (autologous) pluripotent VSELs to treat diabetes in future in addition to other pluripotent stem cells (ES cells or iPS cells) grown in a Petri dish.
The present study further substantiates the presence of a novel population of VSELs in adult mouse pancreas. Evidence is generated to show that regeneration of pancreas involves stem cells. VSELs regenerate adult mouse pancreas and thus may be an ideal candidate for cell therapy compared with ES/iPS cells, which give rise to the fetal counterparts and thus may be of little value to treat age-related diabetes due to loss of islet function. Further studies are required to understand why VSELs (although present in increased numbers) are unable to regenerate STZ-treated mouse pancreas. The study provides an altogether new perspective to the field of stem cell therapy for diabetes.
marker for hemato-lymphoid cells
- H & E:
hematoxylin and eosin
induced pluripotent stem
lineage markers for mature hematopoietic cells
marker to define pluripotent state
pancreas duodenum homeobox-1
marker for mouse VSELs and hematopoietic stem cells
marker to define pluripotent state
very small embryonic-like stem cells.
The study was financially supported by the Indian Council of Medical Research, Government of India, New Delhi, India. Help from Ms Harshada is acknowledged for the histology procedures, and Ms Malati Umarani from the National Centre for Cell Sciences, Pune is thanked for demonstrating the procedure to extract RNA from mouse pancreas and the kind gift of PDX antibody.
- Rankin MM, Wilbur CJ, Rak K, Shields EJ, Granger A, Kushner JA: β-Cells are not generated in pancreatic duct ligation-induced injury in adult mice. Diabetes. 2013, 62: 1634-1645. 10.2337/db12-0848.PubMed CentralView ArticlePubMedGoogle Scholar
- Xiao X, Chen Z, Shiota C, Prasadan K, Guo P, El-Gohary Y, Paredes J, Welsh C, Wiersch J, Gittes GK: No evidence for β cell neogenesis in murine adult pancreas. J Clin Invest. 2013, 123: 2207-2217. 10.1172/JCI66323.PubMed CentralView ArticlePubMedGoogle Scholar
- Bouwens L, Houbracken I, Mfopou JK: The use of stem cells for pancreatic regeneration in diabetes mellitus. Nat Rev Endocrinol. 2013, 9: 598-606. 10.1038/nrendo.2013.145.View ArticlePubMedGoogle Scholar
- Wang RN, Klöppel G, Bouwens L: Duct- to islet-cell differentiation and islet growth in the pancreas of duct-ligated adult rats. Diabetologia. 1995, 38: 1405-1411. 10.1007/BF00400600.View ArticlePubMedGoogle Scholar
- Xu X, D’Hoker J, Stangé G, Bonné S, De Leu N, Xiao X, Van de Casteele M, Mellitzer G, Ling Z, Pipeleers D, Bouwens L, Scharfmann R, Gradwohl G, Heimberg H: Beta cells can be generated from endogenous progenitors in injured adult mouse pancreas. Cell. 2008, 132: 197-207. 10.1016/j.cell.2007.12.015.View ArticlePubMedGoogle Scholar
- Scully T: Diabetes in numbers. Nature. 2012, 485: S2-S3. 10.1038/485S2a.View ArticlePubMedGoogle Scholar
- Zuba-Surma EK, Kucia M, Wu W, Klich I, Lillard JW, Ratajczak J, Ratajczak MZ: Very small embryonic-like stem cells are present in adult murine organs: image stream-based morphological analysis and distribution studies. Cytometry A. 2008, 73A: 1116-1127. 10.1002/cyto.a.20667.PubMed CentralView ArticlePubMedGoogle Scholar
- Kucia M, Wu W, Ratajczak MZ: Bone marrow-derived very small embryonic-like stem cells: their developmental origin and biological significance. Dev Dyn. 2007, 236: 3309-3320. 10.1002/dvdy.21180.View ArticlePubMedGoogle Scholar
- Shin DM, Liu R, Klich I, Wu W, Ratajczak J, Kucia M, Ratajczak MZ: Molecular signature of adult bone marrow-purified very small embryonic-like stem cells supports their developmental epiblast/germ line origin. Leukemia. 2010, 24: 1450-1461. 10.1038/leu.2010.121.View ArticlePubMedGoogle Scholar
- Kucia M, Maj M, Mierzejewska K, Shin DM, Ratajczak J, Ratajczak MZ: Challenging dogmas – or how much evidence is necessary to claim that there is a direct developmental and functional link between the primordial germ cell (PGC) lineage and hematopoiesis? 55th ASH annual Meeting 2013 [abstract 1215]. Blood. 2013, 122: [http://www.bloodjournal.org/content/122/21/1215.short?]Google Scholar
- Kucharska-Mazur J, Tarnowski M, Dołęgowska B, Budkowska M, Pędziwiatr D, Jabłoński M, Pełka-Wysiecka J, Kazimierczak A, Ratajczak MZ, Samochowiec J: Novel evidence for enhanced stem cell trafficking in antipsychotic-naïve subjects during their first psychotic episode. J Psychiatr Res. 2014, 49: 18-24.View ArticlePubMedGoogle Scholar
- Ratajczak MZ, Zuba-Surma E, Wojakowski W, Suszynska M, Mierzejewska K, Liu R, Ratajczak J, Shin DM, Kucia M: Very small embryonic-like stem cells (VSELs) represent a real challenge in stem cell biology: recent pros and cons in the midst of a lively debate. Leukemia. 2014, 28: 473-484. 10.1038/leu.2013.255.PubMed CentralView ArticlePubMedGoogle Scholar
- Starzyńska T, Dąbkowski K, Błogowski W, Zuba-Surma E, Budkowska M, Sałata D, Dołęgowska B, Marlicz W, Lubikowski J, Ratajczak MZ: An intensified systemic trafficking of bone marrow-derived stem/progenitor cells in patients with pancreatic cancer. J Cell Mol Med. 2013, 17: 792-799. 10.1111/jcmm.12065.PubMed CentralView ArticlePubMedGoogle Scholar
- Drukała J, Paczkowska E, Kucia M, Młyńska E, Krajewski A, Machaliński B, Madeja Z, Ratajczak MZ: Stem cells, including a population of very small embryonic-like stem cells, are mobilized into peripheral blood in patients after skin burn injury. Stem Cell Rev. 2012, 8: 184-194. 10.1007/s12015-011-9272-4.View ArticlePubMedGoogle Scholar
- Marlicz W, Zuba-Surma E, Kucia M, Blogowski W, Starzynska T, Ratajczak MZ: Various types of stem cells, including a population of very small embryonic-like stem cells, are mobilized into peripheral blood in patients with Crohn’s disease. Inflamm Bowel Dis. 2012, 18: 1711-1722. 10.1002/ibd.22875.View ArticlePubMedGoogle Scholar
- Wyderka R, Wojakowski W, Jadczyk T, Maślankiewicz K, Parma Z, Pawłowski T, Musiałek P, Majka M, Król M, Kuczmik W, Dworowy S, Korzeniowska B, Ratajczak MZ, Tendera M: Mobilization of CD34+CXCR4+ stem/progenitor cells and the parameters of left ventricular function and remodeling in 1-year follow-up of patients with acute myocardial infarction. Mediators Inflamm. 2012, 2012: 564027-PubMed CentralView ArticlePubMedGoogle Scholar
- Ratajczak MZ, Shin DM, Liu R, Marlicz W, Tarnowski M, Ratajczak J, Kucia M: Epiblast/germ line hypothesis of cancer development revisited: lesson from the presence of Oct-4+ cells in adult tissues. Stem Cell Rev. 2010, 6: 307-316. 10.1007/s12015-010-9143-4.PubMed CentralView ArticlePubMedGoogle Scholar
- Havens AM, Sun H, Shiozawa Y, Jung Y, Wang J, Mishra A, Jiang Y, O’Neill DW, Krebsbach PH, Rodgerson DO, Taichman RS: Human and murine very small embryonic-like (VSEL) cells represent multipotent tissue progenitors in vitro and in vivo. Stem Cells Dev. 2014, 23: 689-701. 10.1089/scd.2013.0362.PubMed CentralView ArticlePubMedGoogle Scholar
- Kucia M, Reca R, Campbell FR, Zuba-Surma E, Majka M, Ratajczak J, Ratajczak MZ: A population of very small embryonic-like (VSEL) CXCR4(+)SSEA-1(+)Oct-4+ stem cells identified in adult bone marrow. Leukemia. 2006, 20: 857-869. 10.1038/sj.leu.2404171.View ArticlePubMedGoogle Scholar
- Kassmer SH, Krause DS: Very small embryonic-like cells: biology and function of these potential endogenous pluripotent stem cells in adult tissues. Mol Reprod Dev. 2013, 80: 677-690. 10.1002/mrd.22168.View ArticlePubMedGoogle Scholar
- Ratajczak MZ, Zuba-Surma E, Kucia M, Poniewierska A, Suszynska M, Ratajczak J: Pluripotent and multipotent stem cells in adult tissues. Adv Med Sci. 2012, 57: 1-17. 10.2478/v10039-012-0020-z.View ArticlePubMedGoogle Scholar
- Bhartiya D, Shaikh A, Nagvenkar P, Kasiviswanathan S, Pethe P, Pawani H, Mohanty S, Rao SG, Zaveri K, Hinduja I: Very small embryonic-like stem cells with maximum regenerative potential get discarded during cord blood banking and bone marrow processing for autologous stem cell therapy. Stem Cells Dev. 2012, 21: 1-6. 10.1089/scd.2011.0311.View ArticlePubMedGoogle Scholar
- Bhartiya D, Unni S, Parte S, Anand S: Very small embryonic-like stem cells: implications in reproductive biology. Biomed Res Int. 2013, 2013: 682326-PubMed CentralView ArticlePubMedGoogle Scholar
- Ratajczak J, Wysoczynski M, Zuba-Surma E, Wan W, Kucia M, Yoder MC, Ratajczak MZ: Adult murine bone marrow-derived very small embryonic-like stem cells differentiate into the hematopoietic lineage after coculture over OP9 stromal cells. Exp Hematol. 2011, 39: 225-237. 10.1016/j.exphem.2010.10.007.PubMed CentralView ArticlePubMedGoogle Scholar
- Hardikar AA, Karandikar MS, Bhonde RR: Effect of partial pancreatectomy on diabetic status in BALB/c mice. J Endocrinol. 1999, 162: 189-195. 10.1677/joe.0.1620189.View ArticlePubMedGoogle Scholar
- Finegood DT, Weir GC, Bonner-Weir S: Prior streptozotocin treatment does not inhibit pancreas regeneration after 90% pancreatectomy in rats. Am J Physiol. 1999, 276: E822-E827.PubMedGoogle Scholar
- Liu T, Wang CY, Gou SM, Wu HS, Xiong JX, Zhou J: PDX-1 expression and proliferation of duct epithelial cells after partial pancreatectomy in rats. Hepatobiliary Pancreat Dis Int. 2007, 6: 424-429.PubMedGoogle Scholar
- Gu G, Dubauskaite J, Melton DA: Direct evidence for the pancreatic lineage: NGN3+ cells are islet progenitors and are distinct from duct progenitors. Development. 2002, 129: 2447-2457.PubMedGoogle Scholar
- Sharma A, Zangen DH, Reitz P, Taneja M, Lissauer ME, Miller CP, Weir GC, Habener JF, Bonner-Weir S: The homeodomain protein IDX-1 increases after an early burst of proliferation during pancreatic regeneration. Diabetes. 1999, 48: 507-513. 10.2337/diabetes.48.3.507.View ArticlePubMedGoogle Scholar
- Scarlett CJ, Colvin EK, Pinese M, Chang DK, Morey AL, Musgrove EA, Pajic M, Apte M, Henshall SM, Sutherland RL, Kench JG, Biankin AV: Recruitment and activation of pancreatic stellate cells from the bone marrow in pancreatic cancer: a model of tumor–host interaction. PLoS One. 2011, 6: e26088-10.1371/journal.pone.0026088.PubMed CentralView ArticlePubMedGoogle Scholar
- Zhao M, Amiel SA, Christie MR, Muiesan P, Srinivasan P, Littlejohn W, Rela M, Arno M, Heaton N, Huang GC: Evidence for the presence of stem cell-like progenitor cells in human adult pancreas. J Endocrinol. 2007, 195: 407-414. 10.1677/JOE-07-0436.View ArticlePubMedGoogle Scholar
- White MG, Al-Turaifi HR, Holliman GN, Aldibbiat A, Mahmoud A, Shaw JA: Pluripotency-associated stem cell marker expression in proliferative cell cultures derived from adult human pancreas. J Endocrinol. 2011, 211: 169-176. 10.1530/JOE-11-0123.View ArticlePubMedGoogle Scholar
- Tai MH, Chang CC, Kiupel M, Webster JD, Olson LK, Trosko JE: Oct4 expression in adult human stem cells: evidence in support of the stem cell theory of carcinogenesis. Carcinogenesis. 2005, 26: 495-502.View ArticlePubMedGoogle Scholar
- Gorjup E, Danner S, Rotter N, Habermann J, Brassat U, Brummendorf TH, Wien S, Meyerhans A, Wollenberg B, Kruse C, von Briesen H: Glandular tissue from human pancreas and salivary gland yields similar stem cell populations. Eur J Cell Biol. 2009, 88: 409-421. 10.1016/j.ejcb.2009.02.187.View ArticlePubMedGoogle Scholar
- Abbott A: Doubt cast over tiny stem cells. Nature. 2013, 499: 390-10.1038/499390a.View ArticlePubMedGoogle Scholar
- Miyanishi M, Mori Y, Seita J, Chen JY, Karten S, Chan CK, Nakauchi H, Weissman IL: Do pluripotent stem cells exist in adult mice as very small embryonic stem cells?. Stem Cell Reports. 2013, 1: 198-208. 10.1016/j.stemcr.2013.07.001.PubMed CentralView ArticlePubMedGoogle Scholar
- Szade K, Bukowska-Strakova K, Nowak WN, Szade A, Kachamakova-Trojanowska N, Zukowska M, Jozkowicz A, Dulak J: Murine bone marrow Lin−Sca−1+CD45− very small embryonic-like (VSEL) cells are heterogeneous population lacking Oct-4A expression. PLoS One. 2013, 8: e63329-10.1371/journal.pone.0063329.PubMed CentralView ArticlePubMedGoogle Scholar
- Alvarez-Gonzalez C, Duggleby R, Vagaska B, Querol S, Gomez SG, Ferretti P, Madrigal A: Cord blood Lin(−) CD45(−) embryonic-like stem cells are a heterogeneous population that lack self-renewal capacity. PLoS One. 2013, 8: e67968-10.1371/journal.pone.0067968.PubMed CentralView ArticlePubMedGoogle Scholar
- Danova-Alt R, Heider A, Egger D, Cross M, Alt R: Very small embryonic-like stem cells purified from umbilical cord blood lack stem cell characteristics. PLoS One. 2012, 7: e34899-10.1371/journal.pone.0034899.PubMed CentralView ArticlePubMedGoogle Scholar
- Suszynska M, Zuba-Surma EK, Maj M, Mierzejewska K, Ratajczak J, Kucia M, Ratajczak MZ: The proper criteria for identification and sorting of very small embryonic-like stem cells (VSELs), and some nomenclature issues. Stem Cells Dev. 2014, 23: 702-713. 10.1089/scd.2013.0472.PubMed CentralView ArticlePubMedGoogle Scholar
- Shin DM, Suszynska M, Mierzejewska K, Ratajczak J, Ratajczak MZ: Very small embryonic-like stem-cell optimization of isolation protocols: an update of molecular signatures and a review of current in vivo applications. Exp Mol Med. 2013, 45: e56-10.1038/emm.2013.117.PubMed CentralView ArticlePubMedGoogle Scholar
- Dor Y, Brown J, Martinez OI, Melton DA: Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation. Nature. 2004, 429: 41-46. 10.1038/nature02520.View ArticlePubMedGoogle Scholar
- Li Z, Manna P, Kobayashi H, Spilde T, Bhatia A, Preuett B, Prasadan K, Hembree M, Gittes GK: Multifaceted pancreatic mesenchymal control of epithelial lineage selection. Dev Biol. 2004, 269: 252-263. 10.1016/j.ydbio.2004.01.043.View ArticlePubMedGoogle Scholar
- Huang Y, Kucia M, Hussain LR, Wen Y, Xu H, Yan J, Ratajczak MZ, Ildstad ST: Bone marrow transplantation temporarily improves pancreatic function in streptozotocin-induced diabetes: potential involvement of very small embryonic-like cells. Transplantation. 2010, 89: 677-685. 10.1097/TP.0b013e3181c9dc7d.PubMed CentralView ArticlePubMedGoogle Scholar
- Johnson J, Bagley J, Skaznik-Wikiel M, Lee HJ, Adams GB, Niikura Y, Tschudy KS, Tilly JC, Cortes ML, Forkert R, Spitzer T, Iacomini J, Scadden DT, Tilly JL: Oocyte generation in adult mammalian ovaries by putative germ cells in bone marrow and peripheral blood. Cell. 2005, 122: 303-315. 10.1016/j.cell.2005.06.031.View ArticlePubMedGoogle Scholar
- Nayernia K, Lee JH, Drusenheimer N, Nolte J, Wulf G, Dressel R, Gromoll J, Engel W: Derivation of male germ cells from bone marrow stem cells. Lab Invest. 2006, 86: 654-663. 10.1038/labinvest.3700429.View ArticlePubMedGoogle Scholar
- Paczkowska E, Kucia M, Koziarska D, Halasa M, Safranow K, Masiuk M, Karbicka A, Nowik M, Nowacki P, Ratajczak MZ, Machalinski B: Clinical evidence that very small embryonic-like stem cells are mobilized into peripheral blood in patients after stroke. Stroke. 2009, 40: 1237-1244. 10.1161/STROKEAHA.108.535062.View ArticlePubMedGoogle Scholar
- Rezania A, Bruin JE, Xu J, Narayan K, Fox JK, O’Neil JJ, Kieffer TJ: Enrichment of human embryonic stem cell derived NKX6.1 expressing pancreatic progenitor cells accelerates the maturation of insulin-secreting cells in vivo. Stem Cells. 2013, 31: 2432-2442. 10.1002/stem.1489.View ArticlePubMedGoogle Scholar
- Bhansali A, Walia R, Bhansali S, Gupta V, Jain A, Sachdeva N, Sharma RR, Marwaha N, Khandelwal N, A P: Efficacy and safety of autologous bone marrow derived stem cell transplantation in patients with type 2 diabetes mellitus: a randomized placebo-controlled study. Cell Transplant. 2013, [Epub ahead of print]Google Scholar
- Pileggi A: Mesenchymal stem cells for the treatment of diabetes. Diabetes. 2012, 61: 1355-1356. 10.2337/db12-0355.PubMed CentralView ArticlePubMedGoogle Scholar
- Volarevic V, Arsenijevic N, Lukic ML, Stojkovic M: Concise review: mesenchymal stem cell treatment of the complications of diabetes mellitus. Stem Cells. 2011, 29: 5-10. 10.1002/stem.556.PubMed CentralView ArticlePubMedGoogle Scholar
- Tabar V, Studer L: Pluripotent stem cells in regenerative medicine: challenges and recent concepts. Nat Genet. 2014, 15: 82-92. 10.1038/nrg3563.View ArticleGoogle Scholar
- Massasa E, Costa XS, Taylor HS: Failure of the stem cell niche rather than loss of oocyte stem cells in the aging ovary. Aging (Albany NY). 2010, 2: 1-2.Google Scholar
- Menge BA, Breuer TG, Ritter PR, Uhl W, Schmidt WE, Meier JJ: Long-term recovery of β-cell function after partial pancreatectomy in humans. Metabolism. 2012, 61: 620-624. 10.1016/j.metabol.2011.09.019.View ArticlePubMedGoogle Scholar
- Anand S, Bhartiya D, Sriraman K, Patel H, Manjramkar DD: Very small embryonic-like stem cells survive and restore spermatogenesis after busulphan treatment in mouse testis. J Stem Cell Res Ther. 2014, 4: 216-doi:10.4172/2157-7633.1000216Google Scholar
- Editorial: Advancing regenerative medicine. Nature Medicine. 2014, 20: 795-
- Dimmeler S, Ding S, Rando TA, Trounson A: Translational strategies and challenges in regenerative medicine. Nat Med. 2014, 20: 814-821. 10.1038/nm.3627.View ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.