Fig. 1
From: Challenges and perspectives of tendon-derived cell therapy for tendinopathy: from bench to bedside
Challenge and future perspectives about differentiation status of tendon-derived cells for therapy. Natural reason of various differentiation status of tendon cells is the complexity of tendon structure (i). A tendon consists of myotendinous junction (MTJ), midsubstance of tendon and enthesis. The different composition of extracellular matrix (ECM) proteins secreted by the tendon cells at different regions of tendon results in the niches difference for cellular differentiation, which leads to three possible scenarios for the tendon cell derived therapy at MTJ, midsubstance of tendon and enthesis (ii). (1) One type of tendon-derived cells can be used for tendon repair at MTJ, midsubstance of tendon and enthesis. (2) Specific types of tendon-derived cells are required for tendon repair at MTJ, midsubstance of tendon and enthesis. (3) One type of tendon-derived cells can be used for tendon repair at MTJ, midsubstance of tendon and enthesis after the modification by distinct cell culture protocols. Pathological reason of various differentiation status of tendon cells is the aberrant differentiation in tendinopathy (iii). Aberrant differentiation of tendon cells triggered by intrinsic and extrinsic signals can lead to heterotrophic ossification, fibrosis, hyalinisation and fatty infiltration (iv). Based on current findings on molecular signals, marker panel is an option for monitoring aberrant differentiation (v). Future perspective for this challenge needs further basic studies on characteristics of tendon cells and clinical studies on the clinical efficacy of different types of tendon cells. If certain differentiation status of tendon cells is essential, molecular modification for tendon cells into desired differentiation status is possible. FAP, fibro/adipogenic progenitor cell