title: Tendon-derived progenitor cells improve healing of collagenase-induced flexor tendinitis.
abstract: Tendinitis is a common and a performance-limiting injury in athletes. This study describes the value of intralesional tendon-derived progenitor cell (TDPC) injections in equine flexor tendinitis. Collagenase-induced tendinitis was created in both front superficial digital flexor (SDF) tendons. Four weeks later, the forelimb tendon lesions were treated with 1 × 107autogenous TDPCs or saline. Tendinitis was also induced by collagenase in one hind SDF tendon, to study the survival and distribution of DiI-labeled TDPCs 1, 2, 4, and 6 weeks after injection. The remaining normal tendon was used as a "control." Twelve weeks after forelimb TDPC injections, tendons were harvested for assessment of matrix gene expression, biochemical, biomechanical, and histological characteristics. DiI-labeled TDPCs were abundant 1 week after injection but gradually declined over time and were undetectable after 6 weeks. Twelve weeks after TDPC injection, collagens I and III, COMP and tenomodulin mRNA levels were similar (p = 0.3) in both TDPC and saline groups and higher (p < 0.05) than normal tendon. Yield and maximal stresses of the TDPC group were significantly greater (p = 0.005) than the saline group's and similar (p = 0.6) to normal tendon. However, the elastic modulus of the TDPC and saline groups were not significantly different (p = 0.32). Histological assessment of the repair tissues with Fourier transform-second harmonic generation imaging demonstrated that collagen alignment was significantly better (p = 0.02) in TDPC group than in the saline controls. In summary, treating collagenase-induced flexor tendon lesions with TDPCs improved the tensile strength and collagen fiber alignment of the repair tissue. Study Design © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2162-2171, 2016.
authors.affiliation: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, 1008 W Hazelwood Drive, Urbana, Illinois, 61802.
authors.forename: Sushmitha S
authors.initials: SS
authors.lastname: Durgam
authors.affiliation: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, 1008 W Hazelwood Drive, Urbana, Illinois, 61802.
authors.forename: Allison A
authors.initials: AA
authors.lastname: Stewart
authors.affiliation: Core Facilities, Institute of Genomic Biology, University of Illinois, Urbana, Illinois, 61801.
authors.forename: Mayandi
authors.initials: M
authors.lastname: Sivaguru
authors.affiliation: Department of Mechanical Science and Engineering, College of Engineering, University of Illinois, Urbana, Illinois, 61801.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Wagoner Johnson
authors.affiliation: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, 1008 W Hazelwood Drive, Urbana, Illinois, 61802.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Stewart
mesh_terms: D000818:Animals; D002470:Cell Survival; D017364:Collagenases; D004195:Disease Models, Animal; D015870:Gene Expression; D006736:Horses; D011897:Random Allocation; D033581:Stem Cell Transplantation; D052256:Tendinopathy / Q000139:chemically induced / Q000628:therapy*; D013710:Tendons / Q000378:metabolism
chemical_list: D017364:Collagenases
keywords: flexor tendon; in vivo; tendinitis; tendon-derived progenitor cells (TDPCs)