The effect of various fat graft preparations on collagenase induced experimental tendinopathy model in rats
Project no. 21885 · Status: Kapanmış (Yayın bekleniyor) · 2020
Summary
Introduction: Tendinosis or tendinitis is a condition arousing from repetitive and constraint movements mostly affecting the active population. Clinical picture is often presented as local pain, tenderness and restriction of daily and sport activities. Chronic tendinopathies comprise 30 to 50% of all sports injuries. Nevertheless, treatment options are not as convenient. The efficacy of rest and stretching of the affected muscles is well established. However, long recovery times and questionable remission rates, especially in the older population, urges the caregivers for new line of treatments including more invasive ones. Steroid and non-steroidal anti-inflammatory drug injections, platelet rich plasma, lazers, shock waves, iontophoresis, sonophoresis, arthroscopic and open debridement surgeries are among many. Although some clinical efficacy of these trreatments has been shown for some patients, the results have been notoriously inconsistent. In this experimental study, a rat model of tendinopathy is established to investigate the benefits of nanofat and microfat emulsions obtained from autologous fat grafts. Material and Methods: 27 Wistar rats aged 8-10 weeks were randomly allocated to three groups. Direct injection of collagenase enzyme into the achilles’ tendons and two weeks of follow up were ensured to establish a chronic tendinopathy in rats. Following this, group 1 received microfat grafts, group 2 received nanofat emulsions, whereas group 3 received phosphate buffer solution (PBS) as controls. After 12 weeks of follow up, the rats were sacrificed and their right achilles tendons were surgically removed. Histologic examinations were made under light microscopy with hematoxylene eosine, Masson trichrome, and Alcian blue stains. A modified Verhofstad scale was used to score the level of tissue damage and inflammation at the sections. Immunhistochemical studies were conducted to determine the distribution of collagen types I and III with CD45 and vimentin markers. Group comparisons and post-hoc tests were conducted according to the distribution pattern of data using SPSS 25 program. Results: In respect of histopathologic findings of tissue healing derived from inflammation and fibrosis Modified Verhofstad scores were significantly lower in the nanofat group in respect to control concerning fibrosis, PMNL infiltration, oedema, collagen, and fibroblast density (P<0.016). Vascularity was higher in both nanofat and microfat groups compared to control (P<0.016). PMNL infiltration, oedema, and collagen density were significantly lower in the nanofat group compared to microfat group (P<0.016). Immunohistochemical studies showed a high immunopositivity against type I collagen antibodies in the nanofat group, whereas lower in the microfat group, and lowest in the control group. Conclusion: In the rat chronic tendinopathy model, nanofat comprised of proportionally higher density of mesenchymal stem cells and stromal vascular fraction derived growth factors histopathologically presented significantly better healing and lower level of inflammation compared to control and microfat emulsions.