Comparison of Stored and Fresh Injectable Acellular Adipose Matrix in Soft Tissue Reconstruction in a Murine Model.

BACKGROUND: We previously showed comparable volume effects of injections of acellular adipose matrix (AAM), an adipose tissue-derived extracellular matrix, and conventional fat grafting in a murine model. Thus, AAM could be a novel allogenic injectable product. However, its retention rate poses a concern, as repeated AAM injections may be required in some cases. This study investigated the biological properties and therapeutic value of stored AAM and compared them with those of fresh AAM, in a murine model. METHODS: AAM was manufactured from fresh human abdominoplasty fat. Fresh and stored injectable AAM was prepared within 24 h and 3 months after generation, respectively. Either fresh or stored injectable AAM was injected into the scalp of athymic nude mice (0.2 mL/sample, n = 6 per group). After 8 weeks, graft retention was assessed through weight measurement, and histological analysis was performed, including immunofluorescence staining for CD31 and perilipin. RESULTS: Retention rate was significantly reduced in the stored compared to the fresh injectable AAM group. Nevertheless, histological analysis revealed comparable inflammatory cell presence, with minimal capsule formation, in both groups. Adipogenesis occurred in both groups, with no significant difference in the blood vessel area (%) between groups. CONCLUSIONS: Although the volume effects of stored AAM for soft tissue reconstruction were limited compared to those of fresh injectable AAM, stored AAM had similar capacity for adipogenesis and angiogenesis. This promising allogeneic injectable holds the potential to serve as an effective "off-the-shelf" alternative for repeated use within a 3-month storage period. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://link.springer.com/journal/00266 .

Effect of Injectable Acellular Adipose Matrix on Soft Tissue Reconstruction in a Murine Model.

BACKGROUND: The extracellular matrix isolated from adipose tissue, known as acellular adipose matrix (AAM), represents a novel biomaterial. AAM functions as a scaffold that not only supports stem cell proliferation and differentiation but also induces adipogenesis and angiogenesis. This study aims to investigate the volumetric effects and microenvironmental changes associated with injectable AAM in comparison to conventional fat grafting. METHODS: AAM was manufactured from fresh human abdominoplasty fat using a mechanically modified method and then transformed into an injectable form. Lipoaspirate was harvested employing the Coleman technique. A weight and volume study was conducted on athymic nude mice by injecting either injectable AAM or lipoaspirate into the scalp (n=6 per group). After eight weeks, graft retention was assessed through weight measurement and volumetric analysis using micro-computed tomography (micro-CT) scanning. Histological analysis was performed using immunofluorescence staining for perilipin and CD31. RESULTS: Injectable AAM exhibited similar weight and volume effects in murine models. Histological analysis revealed comparable inflammatory cell presence with minimal capsule formation when compared to conventional fat grafts. Adipogenesis occurred in both AAM-injected and conventional fat graft models, with no significant difference in the blood vessel area (%) between the two. CONCLUSIONS: In summary, injectable AAM demonstrates effectiveness comparable to conventional fat grafting concerning volume effects and tissue regeneration in soft tissue reconstruction. This promising allogeneic injectable holds the potential to serve as a safe and effective "Off-the-Shelf" alternative in both aesthetic and reconstructive clinical practices. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Histological Comparison of Nanofat and Lipoconcentrate: Enhanced Effects of Lipoconcentrate on Adipogenesis and Angiogenesis.

BACKGROUND: Nanofat and lipoconcentrate contain adipose-derived stem cells and growth factors, and have wide clinical applications in the regenerative field. This study aimed to investigate the microenvironmental changes associated with nanofat and lipoconcentrate. METHODS: Conventional fat, nanofat, or lipoconcentrate (0.2 mL each, n = 5 per group) were injected subcutaneously into the dorsal flanks of athymic nude mice. The graft weights were measured at postoperative week 4; the grafts and their overlying skin were used for histological analyses. RESULTS: Weights of the lipoconcentrate grafts were significantly greater than those of the conventional fat (p < 0.05) and nanofat (p < 0.01) grafts. There was no significant difference in inflammation, oil cysts, and fibrosis between the conventional fat and nanofat groups. Histological examination of the lipoconcentrate grafts showed less macrophage infiltration and the formation of fibrosis and oil cysts. Additionally, adipogenesis and angiogenesis were induced more in the lipoconcentrate grafts than in the nanofat grafts (p < 0.01). Lipoconcentrate and nanofat improved dermal thickness (p < 0.001 and p < 0.01, respectively, versus the baseline). CONCLUSION: Lipoconcentrate grafts had greater volume and shape retention than conventional fat and nanofat grafts. They had better histological structure and acted as scaffolds for adipogenesis and angiogenesis. Both products showed regenerative effects on dermal thickness; however, only lipoconcentrate grafts had the required volume and regenerative effects, allowing it to serve as a novel adipose-free grafting method for facial rejuvenation and contouring. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effects of Nanofat in Plastic and Reconstructive Surgery: A Systematic Review.

BACKGROUND: Since the initial introduction by Tonnard in 2013, numerous studies have reported positive findings after employing nanofat; however, concerns exist regarding its effects and mechanisms, and various methods to generate nanofat also remain unclear. The systematic review was conducted to evaluate the efficacy of sole nanofat grafting in plastic and reconstructive surgery. METHODS: The MEDLINE, Embase, Cochrane Central, Web of Science, and Scopus databases were searched for studies related to sole nanofat grafting in plastic and reconstructive surgery (November 23rd, 2022). Outcomes of interest were all clinical results on humans or animals. RESULTS: Twelve studies were included, and no meta-analysis was conducted due to the clinical heterogeneity of the studies. In general, included studies had a low level of evidence. Six studies (n=253) showed significant improvements in scar characteristics via evaluation of the POSAS scales, FACE-Q scale, physician assessment, patient satisfaction, or VSS scale. Four studies described its benefits in skin rejuvenation (wrinkles, fine rhytides, pigmentation, or discoloration) via photographs, questionnaires, or indentation indices. Histological evaluation illustrated overall increases of skin thickness, collagen, and elastic fibers. Three experimental studies showed beneficial effects of nanofat on fat grafting, diabetic wound healing, and hair growth with compelling histological evidence. No severe complication was reported. CONCLUSION: Sole nanofat grafting shows potential benefits in scar treatment and anti-aging with conclusive histological evidence. Clinical studies about fat grafting, wound healing, or hair growth should be conducted, based on the foundation in this systematic review. Nanofat grafting could be a practical and safe procedure.