Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon L. Tharp Street, Columbus, OH, USA.
BMC Vet Res. 2021 Apr 1;17(1):138. doi: 10.1186/s12917-021-02793-1.
Intrasynovial deep digital flexor tendon (DDFT) injuries occur frequently and are often implicated in cases of navicular disease with poor outcomes and reinjuries. Cell-based approaches to tendon healing are gaining traction in veterinary medicine and ultimately may contribute to improved DDFT healing in horses. However, a better understanding of the innate cellular characteristics of equine DDFT is necessary for developing improved therapeutic strategies. Additionally, fibrocartilaginous, intrasynovial tendons like the DDFT are common sites of injury and share a poor prognosis across species, offering translational applications of this research. The objective of this study is to isolate and characterize tendon-derived cells (TDC) from intrasynovial DDFT harvested from within the equine forelimb podotrochlear bursa. TDC from the fibrocartilaginous and tendinous zones are separately isolated and assessed. Flow cytometry is performed for mesenchymal stem cell (MSC) surface markers (CD 29, CD 44, CD 90). Basal tenogenic, osteogenic and chondrogenic markers are assessed via quantitative real time-PCR, and standard trilineage differentiation is performed with third passage TDC from the fibrocartilaginous (fTDC) and tendinous (tTDC) zones of DDFT.
Low-density plating isolated homogenous TDC populations from both zones. During monolayer passage, both TDC subpopulations exhibited clonogenicity, high in vitro proliferation rate, and fibroblast-like morphology. fTDC and tTDC were positive for MSC surface markers CD90 and CD29 and negative for CD44. There were no significant differences in basal tenogenic, osteogenic or chondrogenic marker expression between zones. While fTDC were largely restricted to chondrogenic differentiation, tTDC underwent osteogenic and chondrogenic differentiation. Both TDC subpopulations displayed weak adipogenic differentiation potentials.
TDC at the level of the podotrochlear bursa, that potentially could be targeted for enhancing DDFT injury healing in horses were identified and characterized. Pending further investigation, promoting chondrogenic properties in cells administered exogenously into the intrasynovial space may be beneficial for intrasynovial tendon regeneration.
滑液内深部指深屈肌腱（DDFT）损伤经常发生，并且常与跗骨疾病相关，这些疾病的预后较差，且容易再次受伤。细胞为基础的肌腱愈合方法在兽医领域中越来越受到关注，最终可能有助于改善马的 DDFT 愈合。然而，为了开发出更好的治疗策略，有必要更好地了解马的 DDFT 的固有细胞特性。此外，滑液内纤维软骨样肌腱（如 DDFT）是常见的损伤部位，在不同物种中预后均较差，为这项研究提供了转化应用的机会。本研究的目的是从马前肢球节滑液内跗骨滑车腱鞘中分离并鉴定滑液内 DDFT 的肌腱源性细胞（TDC）。分别分离和评估纤维软骨和肌腱区的 TDC。通过流式细胞术检测间充质干细胞（MSC）表面标志物（CD29、CD44、CD90）。通过实时定量 PCR 评估基本的腱形成、成骨和成软骨标志物，并对纤维软骨区（fTDC）和肌腱区（tTDC）的第 3 代 TDC 进行三系分化标准实验。
低密度培养分离出了来自两个区的同质 TDC 群体。在单层传代过程中，两种 TDC 亚群均表现出克隆形成能力、高体外增殖率和成纤维细胞样形态。fTDC 和 tTDC 均为 MSC 表面标志物 CD90 和 CD29 阳性，CD44 阴性。区之间基本腱形成、成骨和成软骨标志物的表达无显著差异。fTDC 主要局限于软骨分化，而 tTDC 则经历成骨和软骨分化。两种 TDC 亚群均表现出较弱的成脂分化潜力。
在跗骨滑车腱鞘水平鉴定并鉴定出了可能有助于增强马 DDFT 损伤愈合的 TDC，并对其进行了特征描述。在进一步研究之前，在外源性给予滑液内空间时促进细胞的软骨形成特性可能有利于滑液内肌腱再生。
