Comparative Evaluation of Exosomes, Mesenchymal Stem Cells, and Nanofat on Cartilage Graft Viability in a Rat Model

Cartilage grafts are widely used in aesthetic and reconstructive procedures; however, their long-term success depends on the preservation of chondrocyte viability and extracellular matrix integrity following transplantation. Adipose-derived products, including nanofat, mesenchymal stem cells, and stem cell-derived exosomes, have emerged as potential biological adjuncts to enhance graft survival. This study aimed to compare the effects of nanofat, adipose-derived mesenchymal stem cells (ADMSCs), and ADMSC-derived exosomes on the viability of auricular cartilage grafts in a rat model. We hypothesized that exosome treatment would improve extracellular matrix preservation and increase type II collagen expression.

Twenty-four male Wistar rats (6 months old, approximately 400 g) received four auricular cartilage grafts implanted subdermally into standardized pockets and allocated to four groups: control, nanofat, ADMSCs, and exosomes. The animals were divided into three cohorts according to follow-up duration (4, 12, and 24 weeks; n = 8 per group). Histological evaluation was performed using hematoxylin-eosin, Safranin O/Fast Green, and Toluidine Blue staining to assess morphology and extracellular matrix composition. Collagen type II expression was evaluated by immunohistochemistry and quantified using H-score analysis.

Graft architecture was preserved in all groups without evidence of adverse effects. Nanofat and ADMSC applications demonstrated increased proteoglycan staining compared to controls; however, no significant increase in collagen type II expression was observed. In contrast, exosome treatment resulted in a significant increase in collagen type II expression at 12 weeks (p = 0.035), with sustained improvement observed at 24 weeks.

ADMSC-derived exosomes enhanced cartilage graft viability more effectively than nanofat or ADMSCs. These findings suggest that exosomes may serve as a promising cell-free therapeutic strategy to improve cartilage graft outcomes in reconstructive procedures.

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