Mesenchymal Stem Cell Secretome Improves Tendon Cell Viability In Vitro and Tendon-Bone Healing In Vivo When a Tissue Engineering Strategy Is Used in a Rat Model of Chronic Massive Rotator Cuff Tear

Am J Sports Med. 2018 Feb;46(2):449-459. doi: 10.1177/0363546517735850. Epub 2017 Oct 20.


Background: Massive rotator cuff tears (MRCTs) represent a major clinical concern, especially when degeneration and chronicity are involved, which highly compromise healing capacity.

Purpose: To study the effect of the secretome of mesenchymal stem cells (MSCs) on tendon cells (TCs) followed by the combination of these activated TCs with an electrospun keratin-based scaffold to develop a tissue engineering strategy to improve tendon-bone interface (TBi) healing in a chronic MRCT rat model.

Study design: Controlled laboratory study.

Methods: Human TCs (hTCs) cultured with the human MSCs (hMSCs) secretome (as conditioned media [CM]) were combined with keratin electrospun scaffolds and further implanted in a chronic MRCT rat model. Wistar-Han rats (N = 15) were randomly assigned to 1 of 3 groups: untreated lesion (MRCT group, n = 5), lesion treated with a scaffold only (scaffold-only group, n = 5), and lesion treated with a scaffold seeded with hTCs preconditioned with hMSCs-CM (STC_hMSC_CM group, n = 5). After sacrifice, 16 weeks after surgery, the rotator cuff TBi was harvested for histological analysis and biomechanical testing.

Results: The hMSCs secretome increased hTCs viability and density in vitro. In vivo, a significant improvement of the tendon maturing score was observed in the STC_hMSC_CM group (mean ± standard error of the mean, 15.6 ± 1.08) compared with the MRCT group (11.0 ± 1.38; P < .05). Biomechanical tests revealed a significant increase in the total elongation to rupture (STC_hMSC_CM, 11.99 ± 3.30 mm; scaffold-only, 9.89 ± 3.47 mm; MRCT, 5.86 ± 3.16 mm; P < .05) as well as a lower stiffness (STC_hMSC_CM, 6.25 ± 1.74 N/mm; scaffold-only, 6.72 ± 1.28 N/mm; MRCT, 11.54 ± 2.99 N/mm; P < .01).

Conclusion: The results demonstrated that hMSCs-CM increased hTCs viability and density in vitro. Clear benefits also were observed when these primed cells were integrated into a tissue engineering strategy with an electrospun keratin scaffold, as evidenced by improved histological and biomechanical properties for the STC_hMSC_CM group compared with the MRCT group.

Clinical relevance: This work supports further investigation into the use of MSC secretome for priming TCs toward a more differentiated phenotype, and it promotes the tissue engineering strategy as a promising modality to help improve treatment outcomes for chronic MRCTs.

Keywords: hMSC secretome; massive rotator cuff tear; tendon-bone healing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone and Bones
  • Cell Survival
  • Culture Media, Conditioned
  • Humans
  • Keratins
  • Male
  • Mesenchymal Stem Cell Transplantation*
  • Mesenchymal Stem Cells / metabolism*
  • Random Allocation
  • Rats
  • Rats, Wistar
  • Rotator Cuff / surgery
  • Rotator Cuff Injuries / surgery*
  • Rupture / surgery
  • Tendons / cytology*
  • Tissue Engineering*
  • Tissue Scaffolds


  • Culture Media, Conditioned
  • Keratins