Biologics for tendon repair.

Decellularized tissue and cell-derived extracellular matrices as scaffolds for orthopaedic tissue engineering.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jor.21559

Tendon‐derived stem cells (TDSCs) promote tendon repair in a rat patellar tendon window defect model

Progress in cell-based therapies for tendon repair☆

Tendons and ligaments (T/L) are dense connective tissues of mesodermal origin. During embryonic development, the tendon-specific cells descend from a sub-set of mesenchymal progenitors condensed in the syndetome, a dorsolateral domain of the sclerotome. These cells are defined by the expression of the transcription factor scleraxis (Scx), which regulates tendon formation and several other characteristic genes, such as collagen type I, decorin, fibromodulin, and tenomodulin (Tnmd). In contrast to other mesenchymal progenitors, the genealogy and biology of the tenogenic lineage is not yet fully understood due to the lack of simple and efficient protocols enabling generation of progenitors in vitro. Here, we investigated whether the expression of Scx can lead to the direct commitment of mesenchymal stem cells (MSCs) into tendon progenitors. First, MSC derived from human bone marrow (hMSC) were lentivirally transduced with FLAG-Scx cDNA to establish 2 clonal cell lines, hMSC-Scx and hMSC-Mock. Subsequent to Scx transduction, hMSC underwent cell morphology change and had significantly reduced proliferation and clonogenicity. Gene expression analysis demonstrated that collagen type I and several T/L-related proteoglycans were upregulated in hMSC-Scx cells. When stimulated toward 3 different mesenchymal lineages, hMSC-Scx cells failed to differentiate into chondrocytes and osteoblasts, whereas adipogenic differentiation still occurred. Lastly, we detected a remarkable upregulation of the T/L differentiation gene Tnmd in hMSC-Scx. From these results, we conclude that Scx delivery results in the direct programming of hMSC into tendon progenitors and that the newly generated hMSC-Scx cell line can be a powerful and useful tool in T/L research.

Conversion of Human Bone Marrow-Derived Mesenchymal Stem Cells into Tendon Progenitor Cells by Ectopic Expression of Scleraxis

Tendon ruptures are increasingly common, repair can be difficult, and healing is poorly understood. Tissue engineering approaches often require expansion of cell numbers to populate a construct, and maintenance of cell phenotype is essential for tissue regeneration. Here, we characterize the phenotype of human Achilles tenocytes and assess how this is affected by passaging. Tenocytes, isolated from tendon samples from 6 patients receiving surgery for rupture of the Achilles tendon, were passaged 8 times. Proliferation rates and cell morphology were recorded at passages 1, 4, and 8. Total collagen, the ratio of collagen types I and III, and decorin were used as indicators of matrix formation, and expression of the integrin beta1 subunit as a marker of cell-matrix interactions. With increasing passage number, cells became more rounded, were more widely spaced at confluence, and confluent cell density declined from 18,700/cm2 to 16,100/cm2 ( p = 0.009). No change to total cell layer collagen was observed but the ratio of type III to type I collagen increased from 0.60 at passage 1 to 0.89 at passage 8 ( p < 0.001). Decorin expression significantly decreased with passage number, from 22.9 +/- 3.1 ng/ng of DNA at passage 1, to 9.1 +/- 1.8 ng/ng of DNA at passage 8 ( p < 0.001). Integrin expression did not change. We conclude that the phenotype of tenocytes in culture rapidly drifts with progressive passage.

https://josorge.com/publications/Citations/BBA/019.pdf

Phenotypic drift in human tenocyte culture.

Introduction: Tendon ruptures are increasingly common, repair can be difficult and healing poorly understood. Tissue engineering approaches often require expansion of cell numbers to populate a construct, and maintenance of cell phenotoype is essential for tissue regeneration. Methods: In this study we characterise the phenotype of human Achilles tenocytes and assess how this is affected by passaging. Tenocytes, isolated from tendon samples from 6 patients receiving surgery for rupture of the Achilles tendon, were passaged 8 times. Proliferation rates and cell morphology were recorded at passages 1, 4 and 8. Total collagen, the ratio of collagen types I and III and decorin were used as indicators of matrix formation and expression of the integrin ‘alpha’1 subunit as a marker of cell-matrix interactions. Results: With increasing passage number, cells became more rounded, were more widely spaced at confluence and confluent cell density declined from 18700 /cm2 to 16100 /cm2 (P=0.009). No change to total cell layer collagen was observed but the ratio of type III to type I collagen increased from 0.60 at passage 1 to 0.89 at passage 8 (P Conclusion: We conclude that the phenotype of tenocytes in culture rapidly drifts with progressive passage.

Phenotypic drift in human tenocyte culture

The biochemical mechanisms underlying tendinopathy are obscure. We briefly describe preliminary observations of human tenocyte behaviour in culture as a vehicle for determining the role of reactive oxygen in tendon pathology.

http://elea.unisa.it:8080/jspui/bitstream/10556/512/1/L.%20Yao%2c%20C.S.%20Bestwick%2c%20%20L.A.%20Bestwick%2c%20R.M%20Aspden%2c%20%20N.%20Maffulli%20-%20NON-IMMORTALIZED%20HUMAN%20TENOCYTE%20CULTURES%20AS%20A%20VEHICLE%20FOR%20UNDERSTANDING%20CELLULAR%20ASPECTS%20TO%20TENDINOPATHY%20%28173-194%29.pdf

L. A. Bestwick

Papers

Phenotypic drift in human tenocyte culture.

Phenotypic drift in human tenocyte culture

Non-immortalized human tenocyte cultures as a vehicle for understanding cellular aspects to tendinopathy.