Histological Analysis of the Effect of Nanofat Grafting in Scar Rejuvenation

Abstract

Introduction: The morphology and tissue response to macro- and micro-fat grafting have been widely studied in both clinical and experimental settings; the histological effects of the nanofat graft, however, remain largely unexplored.

Aims: This study was carried out to evaluate the histological changes leading to scar rejuvenation in a fine scar following nanofat grafting.

Materials and methods: This was an experimental study carried out on guinea-pig fine-line scar models. Nanofat prepared from abdominal fat of the animal was injected into scar on right legs (NFG) at 1 month whereas left acted as controls (CG). Punch biopsies from all scars were analyzed at 2, 4, and 6 months by Hematoxylin&Eosin, Masson's trichrome, and Picrosirius red stains to evaluate dermal/epidermal regeneration, collagen fiber orientation, pattern of distribution, and amount of mature and immature collagen.

Results: Nine animals were included in the final analysis of the study. On histological analysis, the amount of inflammatory infiltrate, collagen fiber orientation, pattern and total histological score at 2, 4, and 6 months were similar between the groups. There was an increased trend for earlier appearance of organized and mature forms of collagen in the NFG group. The distribution of collagen was similar at 2 months; however, there was a significant increase in collagen distribution in NFG at 4 months (NFG: 46.11±11.6, CG: 31.16±9.9; P = 0.010) and at 6 months (NFG: 63.48± 6.6, CG: 49.9 ±8.8; P = 0.002).

Conclusion: Nanofat grafting is associated with an accelerated and increased production of mature collagen with proper alignment in fine-line scars.

Keywords: Collagen; Tonnard; fat grafting; icrosirius red; scar remodeling.

Figure 1

Study procedure. (A) Full thickness surgical incision; (B) sutured surgical wound; (C) harvest of abdominal fat. Inset: Prepared nanofat solution after emulsification of fat harvested. (D) Nanofat injection in the fine-line scar at intradermal and subdermal levels

Figure 2

Microphotographs of the punch biopsy specimens (10×, H&E) and MTC staining. Bright field microscopy showing collagen changes at 2 (A, D), 4 (B, E), and 6 (C, F) months. Upper row: Nanofat-grafted scar demonstrating increase in amount and maturation of collagen with time. (A) At 2 months; (A1): immature collagen with mixed arrangement of fibers with no fascicles. Few inflammatory cells noted in the upper dermis. A2: same is evident in MTC stain. (B) At 4 months; (B1): increase in mature collagen with appearance of fascicles in the lower dermis, (B2): same is evident in MTC stain. (C) At 6 months; (C1): the collagen is more dense with more number of fascicles, (C2): MTC stain depicting the same. Inset in (A1), (B1), and (C1) shows zoomed images to better depict the collagen arrangement. Lower row: Collagen changes in the control group (D) at 2 months; (E) at 4 months; (F) at 6 months. No significant differences noted in the two groups except for more immature collagen in the latter group at 2 months

Figure 3

Comparison of trend of amount of collagen showing significant increase at 4 (P = 0.010) and 6 months (P = 0.002); *Mann–Whitney U-test

Figure 4

Picrosirus red staining (under polarized light microscope) of the punch biopsy specimens showing red collagen fibers with yellow green immature fibers. Upper row: Nanofat-grafted scar demonstrating significantly increased amount of collagen (mainly red fibers depicting mature collagen). (A) At 2 months; (B) at 4 months; (C) at 6 months. Lower row: The control group demonstrating lesser amount of collagen when compared with the nanofat group with time. (D) At 2 months; (E) at 4 months; (F) at 6 months. Note that the majority of the collagen noted are yellow green immature fibers.