Objective: Chronic tendinopathy is a prevalent condition with long recovery times, often necessitating treatments beyond conventional methods like rest and stretching. This study aimed to evaluate the regenerative and anti-inflammatory effects of nanofat and microfat grafts in a collagenase-induced rat model of Achilles tendinopathy.
Materials and Methods: Using collagenase injections, a chronic Achilles tendinopathy model was induced in 27 Wistar albino rats. The rats were randomly divided into three groups: Group 1 received microfat grafts, Group 2 received nanofat grafts, and Group 3 (control) received phosphate-buffered saline (PBS). Nanofat and microfat grafts were prepared from the inguinal fat pads of the rats. Histological and immunohistochemical analyses were performed 12 weeks after treatment.
Results: The nanofat group exhibited significantly lower Modified Verhofstad scores compared to the control group, particularly for fibrosis, polymorphonuclear leukocyte (PMNL) infiltration, edema, collagen, and fibroblast density (p<0.016). Both the nanofat and microfat groups demonstrated significantly higher vascularity compared to the control group (p<0.016). The nanofat group showed significantly less PMNL infiltration, edema, and greater collagen density than the microfat group (p<0.016). Immunohistochemistry revealed the highest immunopositivity for type I and type III collagen in the nanofat group, while the control group showed the lowest levels. CD45 immunoreactivity was most diffuse in the control group and minimal in the nanofat group.
Conclusion: Nanofat, enriched with mesenchymal stem cells and growth factors, significantly improved histopathological outcomes and reduced inflammation compared to microfat and control treatments in a chronic Achilles tendinopathy rat model. These findings suggest that nanofat grafts may offer a minimally invasive and effective treatment for chronic tendinopathy.