The combined use of kartogenin and platelet-rich plasma promotes fibrocartilage formation in the wounded rat Achilles tendon entheses

Abstract

ObjectivesAfter an injury, the biological reattachment of tendon to bone is a challenge because healing takes place between a soft (tendon) and a hard (bone) tissue. Even after healing, the transition zone in the enthesis is not completely regenerated, making it susceptible to re-injury. In this study, we aimed to regenerate Achilles tendon entheses (ATEs) in wounded rats using a combination of kartogenin (KGN) and platelet-rich plasma (PRP).MethodsWounds created in rat ATEs were given three different treatments: kartogenin platelet-rich plasma (KGN-PRP); PRP; or saline (control), followed by histological and immunochemical analyses, and mechanical testing of the rat ATEs after three months of healing.ResultsHistological analysis showed well organised arrangement of collagen fibres and proteoglycan formation in the wounded ATEs in the KGN-PRP group. Furthermore, immunohistochemical analysis revealed fibrocartilage formation in the KGN-PRP-treated ATEs, evidenced by the presence of both collagen I and II in the healed ATE. Larger positively stained collagen III areas were found in both PRP and saline groups than those in the KGN-PRP group. Chondrocyte-related genes, SOX9 and collagen II, and tenocyte-related genes, collagen I and scleraxis (SCX), were also upregulated by KGN-PRP. Moreover, mechanical testing results showed higher ultimate tensile strength in the KGN-PRP group than in the saline control group. In contrast, PRP treatment appeared to have healed the injured ATE but induced no apparent formation of fibrocartilage. The saline-treated group showed poor healing without fibrocartilage tissue formation in the ATEs.ConclusionsOur results show that injection of KGN-PRP induces fibrocartilage formation in the wounded rat ATEs. Hence, KGN-PRP may be a clinically relevant, biological approach to regenerate injured enthesis effectively.Cite this article: J. Zhang, T. Yuan, N. Zheng, Y. Zhou, M. V. Hogan, J. H-C. Wang. The combined use of kartogenin and platelet-rich plasma promotes fibrocartilage formation in the wounded rat Achilles tendon entheses. Bone Joint Res 2017;6:231–244. DOI: 10.1302/2046-3758.64.BJR-2017-0268.R1.

Kartogenin Enhances Collagen Organization and Mechanical Strength of the Repaired Enthesis in a Murine Model of Rotator Cuff Repair

“…10,11 Zhou et al 11 compared the effects of KGN-PRP, PRP alone, or saline injection on tendon—bone healing within a bone tunnel in rats. At 8 weeks, the authors reported significantly higher pull-out strengths of the tendon graft from the bone tunnel in the KGN-PRP group compared with the PRP and saline control groups.…”

“…10 Therefore, each 7 μL of fibrin sealant bead contained 0.224 μg of KGN and 0.002 μL of DMSO. Similarly, control beads containing only DMSO and fibrin sealant were also prepared such that each bead contained an identical amount of DMSO present in each KGN bead (0.03% DMSO).…”

“…In their studies, KGN treatment enhanced production of collagens I and II and increased expression of Sox-9 and scleraxis, consistent with the formation of fibrocartilage-like tissue. 10 Additionally, KGN treatment resulted in more organized collagen fibers and chondrocytes at the tissue interface, and KGN-treated tendon—bone constructs demonstrated greater mean ultimate strengths compared with saline control. 7,10 However, whether KGN can promote the formation of fibrocartilage-like tissue and/or improve the organization of collagen fibers within a healing rotator cuff tendon after its surgical repair is unknown.…”

“…10 Additionally, KGN treatment resulted in more organized collagen fibers and chondrocytes at the tissue interface, and KGN-treated tendon—bone constructs demonstrated greater mean ultimate strengths compared with saline control. 7,10 However, whether KGN can promote the formation of fibrocartilage-like tissue and/or improve the organization of collagen fibers within a healing rotator cuff tendon after its surgical repair is unknown. Augmentation of rotator cuff healing to generate a biomechanically stronger tendon-to-bone interface could result in substantial improvements in the functional outcomes of rotator cuff repair.…”

“…6,7, The chondrogenesis induction properties of KGN have been investigated as a potential chondroprotective therapy for osteoarthritis 6,8 and as a supplement to microfracture for the treatment of full-thickness cartilage defects. 9 Recently, Wang et al 7,10,11 have studied the use of KGN, in combination with platelet-rich plasma (PRP), to facilitate fibrocartilage formation at the interface between tendon and bone, in an attempt to recreate the fibrocartilage zones of the native enthesis. In their studies, KGN treatment enhanced production of collagens I and II and increased expression of Sox-9 and scleraxis, consistent with the formation of fibrocartilage-like tissue.…”