A Combination of Oxo-M and 4-PPBP as a potential regenerative therapeutics for tendon injury

Abstract

Tendons injuries frequently result in scar-like tissue with poor biochemical structure and mechanical properties. We have recently reported that CD146 + perivascular originated tendon stem/progenitor cells (TSCs), playing critical roles in tendon healing. Here, we identified highly efficient small molecules that selectively activate endogenous TSCs for tendon regeneration. Methods : From a pool of ERK1/2 and FAK agonists, Oxo-M and 4-PPBP were identified, and their roles in tenogenic differentiation of TSCs and in vivo tendon healing were investigated. Controlled delivery of Oxo-M and 4-PPBP was applied via PLGA µS. Signaling studies were conducted to determine the mechanism for specificity of Oxo-M and 4-PPBP to CD146 + TSCs. Results : A combination of Oxo-M and 4-PPBP synergistically increased the expressions of tendon-related gene markers in TSCs. In vivo , delivery of Oxo-M and 4-PPBP significantly enhanced healing of fully transected rat patellar tendons (PT), with functional restoration and reorganization of collagen fibrous structure. Our signaling study suggested that Oxo-M and 4-PPBP specifically targets CD146 + TSCs via non-neuronal muscarinic acetylcholine receptors (AChR) and σ1 receptor (σ1) signaling. Principal conclusions : Our findings demonstrate a significant potential of Oxo-M and 4-PPBP as a regenerative therapeutics for tendon injuries.

Effect of local anesthetics on viability and differentiation of various adult stem/progenitor cells

“…These findings may have a substantial clinical impact as LAs are frequently applied during the procedures to isolate stem/progenitor cells from adult tissues for regenerative medicine [ 3 , 11 , 16 ]. Moreover, the long-lasting side effect of LAs can be detrimental to the emerging in situ regeneration application that requires LAs administration during surgical procedures for delivering bioactive cues to recruit and/or stimulate endogenous stem/progenitor cells [ 14 , 20 – 23 ].…”

“…Human tenocytes harvested from the patellar tendons upon total knee replacement were purchased from a commercial provider (Zen-Bio, Inc., Research Triangle Park, NC), to be used as a non-stem/progenitor cell control. Tendon stem/progenitor cells (TSCs) were isolated from surgical tendon debris by sorting primary tendon cells with surface expression of CD146 following our established method [20,23].…”

“…The procedure for isolating adult stem/progenitor cells mostly requires the administration of LAs [14][15][16][17][18]. Moreover, we and others have made promising progress in an emerging field of in situ regeneration which is to guide the regeneration of various tissues by recruiting and activating endogenous stem/progenitor cells [19][20][21][22][23]. In situ regeneration approaches, mostly requiring delivery of bioactive cues with or without scaffolds, necessitate administration of LAs during the surgical and non-surgical procedures [14,15,[19][20][21][22][23].…”

“…Moreover, we and others have made promising progress in an emerging field of in situ regeneration which is to guide the regeneration of various tissues by recruiting and activating endogenous stem/progenitor cells [19][20][21][22][23]. In situ regeneration approaches, mostly requiring delivery of bioactive cues with or without scaffolds, necessitate administration of LAs during the surgical and non-surgical procedures [14,15,[19][20][21][22][23]. Accordingly, it is important to understand the potential effects of LAs not only on short-term cell viability but also on multilineage differentiation afterward.…”

Oxo-M and 4-PPBP Delivery via Multi-Domain Peptide Hydrogel Toward Tendon Regeneration

“…Further investigation into molecular mechanisms of action led us to the discovery of a combination of small molecules, Oxo-M and 4-PPBP sharing intracellular signaling with CTGF, which promotes tendon healing by harnessing endogenous TSCs (26). In addition, our data suggested that Oxo-M and 4-PPBP specifically target CD146 + TSCs via muscarinic acetylene receptors (AChRs) and sigma 1 receptor (σ1R) pathways (26). Given no need for cell isolation, culture-expansion and transplantation, in situ tendon regeneration by delivery of Oxo-M and 4-PPBP has significant translational potential (27).…”