Intrasynovial
tendon injuries are among the most challenging in orthopedics. Despite significant improvements in operative and rehabilitation methods, functional outcomes continue to be limited by adhesions, gap formation, and
rupture. Adhesions result from excessive
inflammation, whereas tendon gapping and
rupture result from
inflammation-induced matrix degradation and insufficient regeneration. Therefore, this study used a combined treatment approach to modulate
inflammation with adipose-derived mesenchymal stromal cells (ASCs) while stimulating tendon regeneration with
connective tissue growth factor (CTGF). ASCs were applied to the repair surface via cell sheets and CTGF was delivered to the repair center via porous
sutures. The effect of the combined treatment was assessed fourteen days after repair in a canine flexor
tendon injury model. CTGF, either alone or with ASCs, reduced inflammatory (IL1B and
IL6) and matrix degrading (MMP3 and MMP13) gene expression, while increasing anti-inflammatory gene (
IL4) expression and
collagen synthesis compared to control repairs. The combined treatment was more effective than CTGF treatment alone, reducing the inflammatory IFNG and
scar-associated COL3A1 gene expression and increasing CD146+ tendon stem/progenitor cells at the tendon surface and interior along the core
suture tracks. Therefore, the combined approach is promising in promoting early flexor tendon healing and worthy of further investigation.