Hepatocyte Growth Factor-Induced Tendon Stem Cell Conditioned Medium Promotes Healing of Injured Achilles Tendon

Abstract

Tendon repair is a medical challenge. Our present study investigated the effectiveness of acellular therapy consisting of conditioned medium (CM) of tendon stem cells (TSCs) induced with hepatocyte growth factor (HGF) in promoting the healing of injured Achilles tendon in a rat model. Proteomic analysis of soluble substances in the CM was performed using an array chip, and bioinformatic analysis was carried out to evaluate interactions among the factors. The effects of CM on viability and migratory capacity of tendon fibroblasts derived from rats with ruptured Achilles tendon were evaluated with the Cell Counting Kit 8 and wound healing assay, respectively. The expression of extracellular matrix (ECM)-related protein was assessed by western blotting. Rats with Achilles tendon injury were treated with CM by local injection for 2 weeks, and the organization of tendon fibers at the lesion site was evaluated by hematoxylin and eosin and Masson’s trichrome staining of tissue samples. The deposition and degradation of ECM proteins and the expression of inflammatory factors at the lesion site were evaluated by immunohistochemistry and immunofluorescence. Biomechanical testing was carried out on the injured tendons to assess functional recovery. There were 12 bioactive molecules in the CM, with HGF as the hub of the protein–protein interaction network. CM treatment enhanced the viability and migration of tendon fibroblasts, altered the expression of ECM proteins, promoted the organization of tendon fibers, suppressed inflammation and improved the biomechanics of the injured Achilles tendon. These results suggest that HGF stimulates the secretion of soluble secretory products by TSCs and CM promotes the repair and functional recovery of ruptured Achilles tendon. Thus, HGF-induced TSC CM has therapeutic potential for the treatment of tendinopathy.

Scaffold-Mediated Immunoengineering as Innovative Strategy for Tendon Regeneration

“…Although most of the studies describing the incorporation of bioactive molecules were performed on randomly oriented fibers [ 85 , 153 , 155 , 157 , 161 , 165 , 171 , 172 ], which do not mimic tendon structure, their description can be of great interest since they could represent novel immunoinformed strategies to develop functionalized tendon biomimetic scaffolds aimed at boosting scaffold’s efficacy and its regenerative potential [ 85 , 153 , 155 , 157 , 161 , 165 , 171 , 172 ]. Within these investigations, a wide range of biomolecules used can be found.…”

“…Apart from the studies regarding the effects of the bioactive molecules on improving the teno-inductive potential of electrospun scaffolds, other investigations concerning the use of different kinds of biocompounds to improve the modulatory effects of the immune system in tenocytes and stem cells were performed [ 163 , 164 , 165 , 166 ]. As previously mentioned, some pro-inflammatory molecules such as IFN-γ induce the secretion of immunomodulatory proteins, such as COX-2, PGE 2 or IDO [ 177 ] in the MSCs.…”

“…Instead, no effect was detected in the transcription levels of EGF, IL-10, TGF-β and MMP-13 [ 166 ]. In a different scenery, Zhang et al performed an experiment in which tendon fibroblasts were cultured in a conditioned medium from tendon stem cells enriched with a gradually increased concentration of HGF [ 165 ]. In these circumstances, there was an upregulation of MMP-2 and MMP-9, α-SMA, TIMP-1 and VEGF in the ECM, as well as the anti-inflammatory cytokines such as IL-10.…”

Combination of Hyaluronan and Lyophilized Progenitor Cell Derivatives: Stabilization of Functional Hydrogel Products for Therapeutic Management of Tendinous Tissue Disorders

“…To further illustrate the differences in scale between the detected quantities of proteins in the studied tenocyte-derived lyophilized APIs and the reported therapeutic doses of the same proteins, selected publications in the field of regenerative medicine presenting the use of individual growth factors were analyzed [50][51][52][53]. Akita et al have reported and discussed the use of FGF-2 at doses of 100 µg/mL in wound healing applications, which correspond to the approved growth factor concentration for skin ulcers in human patients [50].…”

“…Akita et al have reported and discussed the use of FGF-2 at doses of 100 µg/mL in wound healing applications, which correspond to the approved growth factor concentration for skin ulcers in human patients [50]. Zhang et al have reported the use of tendon stem cell (i.e., stimulated with 10-80 ng/mL HGF) conditioned medium for the healing promotion of injured Achilles tendons [51]. Hagerott et al have described the treatment of murine dermal wounds using topical FGF-1 in quantities of 0.6-6.0 µg/cm 2 [52].…”