Table 1 Overview of progenitor cell tissue sources

Bone marrow[31–33, 44]

Twenty to fifty percent of cells are tri-potent Contains specifically chondroprogenitor subpopulations

High expansion potential

Heterogeneous population of cells

Contains fewer CFU-Fs compared to other cell sources

Invasive procedure to harvest

CD105⁺, CD73⁺, CD44⁺, CD90⁺, CD271⁺, CD14⁺, CD13⁺, CD166⁺, CD34^-, CD45^-, CD117^-, CD31^-, VEGFR-2^-

Synovium and synovial fluid [38, 44]

High expansion potential regardless of donor age Superior chondrogenic differentiation potential

No reduction in cell number or potential with donor age

Increase in progenitor cell numbers in early OA

Heterogeneous population of cells

CD105⁺, CD73⁺, CD44⁺, CD90⁺, CD271⁺, CD13⁺, CD166⁺, CD10^-, CD34^-, CD45^-, CD117^-, CD31^-, VEGFR-2

Infrapatellar fat pad [40, 44]

Abundant source of progenitor cells

Superior retention of differentiation potential upon expansion

Comparable differentiation capacity to other tissue sources

Relatively early senescence

CD105⁺, CD73⁺, CD44⁺, CD166⁺, CD271⁺, CD13⁺, CD90⁺, CD34^-, CD45^-, CD31^-, VEGF-2^-

Tendon [43]

Tri-potent cell population, positive chondrogenic differentiation, however, excelling in osteo- and adipogenic potential

Significant expansion potential

Low availability of autologous tendon tissue Minimal chondrogenic capacity

CD105⁺, CD73⁺, CD44⁺, CD90⁺, CD271⁺, CD13⁺, CD166⁺, CD14^-, CD34^-, CD45^-, CD117^-, CD31^-, VEGFR-2^-

Periosteum [28]

Progenitors are multi-potent

Significant in vitro expansion potential and clonogenicity despite donor age

Consists of a heterogeneous population of cells

Invasive harvest procedure

CD105⁺, CD166⁺, CD13⁺, CD73⁺, D7-FIB⁺, CD90⁺, CD44⁺, CD10⁺, CD34^-, CD45^-, CD117^-, CD31^-, VGFR-2^-