Table 2.
Summary of results and characteristics of the studies which investigated the effects of TSPCs in tendon healing.
| Animal type | Models establish | Dosage | Time postoperation | Outcome | Conclusion | Reference |
|---|---|---|---|---|---|---|
| GFP-positive transgenic male rats | Achille tenotomy and repair | GFP-TSC sheet | 2, 4 weeks | Round shaped cells↑ cell numbers, ECM↑ Tnmd, and type I collagen↑ Ultimate Strength↑ | Better cellular alignment, elongation, and densely aligned collagen arrangement in the regenerated tissue at the TSC sheet grafted tendon defect area was observed | [67] |
| Non-GFP SD male rats | Patellar tendon window injury | GFP-TDSC, CTGF ascorbic acid | 2, 4, 8, 16 weeks | Ultimate stress↑ collagen fibers↑ spindle-shaped cells↑ ectopic mineralized tissues↓ | The transplantation of TDSCs promoted tendon repair up to week 16 | [64] |
| Young adult horses | Flexor tendinitis induced by collagenase | TSPCs: 5 × 106 TSPCs in 0.15 ml of sterile phosphate-buffered saline | 1, 2, 4, 6, 12 weeks | Type I collagen, COMP, and tenomodulin mRNA↑ maximum stresses↑ collagen fibers were significantly more aligned | Treatment of collagenase-induced flexor tendon injury with TSPCs not only improved the tensile strength of the repaired tissue, but also improved collagen fiber alignment | [73] |
| SD male rats | Window wound in the patellar tendon and repair | NA | 3, 7, 14 days 4, 6, 8 weeks | CD44+, Sca+↑ Scx, Tnmd, smad8↑ Oct4+, Nanog+, SOX2+, nucleostemin+ CD146↑ | The LRCs participated in tendon repair after injury via migration, proliferation, activation for tenogenesis, and increased pluripotency in the window wound | [15] |
| SD rats | Patellar tendon window injury | GFP-TDSC fibrin | 1, 2, 4, 8, 16 weeks | Fiber arrangement ↑CD3, CD68 (1, 2 weeks) ↓CD163↓ Vascular distribution↓ transplanted cells↓ | Transplantation of allogeneic TSPCs to patellar tendon injury sites in rats not only promotes tendon healing, but also shows a weak immune response | [53] |
| SD rats | PT transection and repair | NA | 2 days 1, 2 weeks | CD 146+TSC ↑TIMP-3↑ IL-10↑ IL-6↓ | CTGF delivery improves the quality of tendon healing by activating TSPCs. Similarly, TSPCs have an anti-inflammatory effect | [16] |
| Female rabbits | Rotator cuff tendon defect | Cell-seeded scaffold (knitted silk—collagen sponge + collagen gel containing allogenous rTSPCs) | 4, 8, 12 weeks | Collagen I, collagen III, Bgn, and TNC ↑ fibroblastic cells↑ stiffness, maximum force, emerge, modulus, and stress at failure↑ | Allogenous TSPC-seeded scaffolds can promote healing of rotator cuff injury | [49] |
| SD rats | Achilles tendon defect | Seeded with TSPCs (ECM + TSPCs group, N = 12, 5 × 105 cells per scaffold) | 4 weeks | Organized collagen fiber structures↑ fibroblast-like cells↑ collagen type I ↑stiffness↑ | The tendon ECM scaffold inoculated with TSPCs not only promotes cell proliferation and stimulates collagen synthesis, but also improves the mechanical properties of the healing tendon | [74] |
| Outbred non-GFP SD male rats | Patellar tendon Window injury | NA | 2, 4, 8 weeks | mRNA expression of Scx ↑Swelling of the knee↓ degree of inflammation↓ fiber arrangement↑ ultimate stress↑ collagen type I↑ | GFP-TDSC-Scx group might promote early tendon repair by increasing the expression of collagen type I in the window wound | [68] |
| Male outbred SD rats | ACL excision and reconstruction | GFP-TDSC sheet | 2, 6, 12 weeks | Cell alignment ↑collagen birefringence↑ ultimate load↑ | The TDSC sheet improved early graft healing after ACL reconstruction in the rat model | [75] |
| SD rats | Achilles tendon rupture and repair | CM (HGF + TSCs) | 2 weeks | MMP-2, MMP-9↑ VEGF↑ Biomechanical properties↑ | CM treatment promotes repair and functional recovery of Achilles tendon ruptures | [76] |
Note: ↑, significant increase; ↓, significant decrease. NA, not applicable; TSPCs, human tendon stem/progenitor cells; Bgn, biglycan; CTGF, connective tissue growth factor; TNC, tenascin-C; COMP, cartilage oligomeric matrix protein; LRCs, label-retaining cells; Tnmd, tenomodulin; Scx, scleraxis; ECM, extracellular matrix; ACL, anterior cruciate ligament; MMP-2, matrix metallopeptidase 2; MMP-9, matrix metallopeptidase 2; VEGF, vascular endothelial growth factor, HGF, hepatocyte growth factor.