Optimization of the Parameters of Different Purification Techniques and Comparison of Their Purification Efficiency and Their Effects on the Metabolic Activity of Adipose Tissue in Autologous Fat Transplantation:

Study on the Application of Concentrated Growth Factor Combined With Adipose Transplantation in Repairing Depressed Deformities of Soft Tissue in the Face

BACKGROUND

Autologous fat is a rich source of adipose tissue that is safe for transplantation. Decreasing the long-term absorption rate is key to improve the survival of transplanted adipose tissue. The aim of this study was to assess the effect of concentrated growth factor (CGF) on the survival of transplanted adipose tissue for repair of facial depression malformations.

METHODS

Coleman adipose granules (CAGs) were prepared from venous blood. In the animal experiment, the ears of 30 healthy male New Zealand white rabbits were randomly allocated to 1 of 4 groups: CGF + CAG (CGF group), platelet-rich fibrin (PRF) + CAG (PRF group), CAG alone (CAG group), and adipose granule transplantation group (control group). Postoperative survival of the transplanted adipose tissue was assessed, the survival and absorption rates of adipose were calculated, and immunohistochemical analysis of specimens was conducted by staining with hematoxylin and eosin and Oil Red O. Of 43 outpatients, 22 received simple adipose transplantation and 21 received autologous CGF combined with adipose transplantation. The adipose absorption rate, complication rate, and cosmetic improvement of the 2 groups were compared.

RESULTS

More adipocytes that are normal were observed in the CGF group, with fewer vacuoles and more uniform distribution of adipose tissue. Survival of the adipose tissue was superior in the CGF and PRF groups. Meanwhile, vascular density and long-term stability were better in the CGF group than the PRF group. In terms of clinical efficacy, the uniformity and survival rate of the adipose tissue were relatively improved in the CGF group compared with the simple adipose particle transplantation group, with less early liquefaction.

CONCLUSION

Concentrated growth factor stabilized and improved the survival of transplanted adipose tissue for filling of facial depression malformations.

The Importance of Protecting the Structure and Viability of Adipose Tissue for Fat Grafting

BACKGROUND

Fat grafting is widely used for soft-tissue augmentation; however, the related clinical outcome remains variable and technique-dependent. The mechanisms underlying fat graft survival are not fully understood, particularly regarding the contributions of different cell types, such as functional adipocytes. This study evaluated the importance of adipose tissue structure and viability in fat grafting and, to some extent, revealed the effect of adipocytes in fat grafting.

METHODS

Human lipoaspirate was harvested using suction-assisted liposuction and processed using three separate methods: cotton-pad filtration, soft centrifugation (400 g for 1 minute), and Coleman centrifugation (1200 g for 3 minutes). Then all samples were subjected to second cotton-pad concentration. Adipose tissue structure and viability, the numbers of adipose-derived stem cells, and their proliferation and multilineage differentiation abilities were compared in vitro. The volume retention rate and fat graft quality were evaluated in vivo.

RESULTS

Cell structure destruction and viability decline were more evident in the Coleman centrifugation group compared to the cotton-pad filtration group and the soft centrifugation group. However, no intergroup differences were observed in the numbers, proliferation, or multilineage differentiation abilities of adipose-derived stem cells. After transplantation, the volume retention rates were similar in the three groups. However, greater structural and functional damage was associated with poorer graft quality, including decreased levels of graft viability, vessel density, and vascular endothelial growth factor secretion and increased levels of vacuoles, necrotic areas, fibrosis, and inflammation.

CONCLUSIONS

Protecting adipose tissue structure and viability is crucial for improving fat grafting outcomes.

CLINICAL RELEVANCE STATEMENT

The protection of the structure and viability of adipose tissue should be ensured throughout the whole process of fat grafting to reduce complications and improve graft quality.

Long-Term Effects of Platelet-Rich Fibrin on Fat Graft Survival and Their Optimal Mixing Ratio

BACKGROUND

Platelet-rich fibrin (PRF) can promote fat graft survival, but the reported mixing ratio of PRF to fat ranges from 1:25 to 1:2, lacking a clear standard for clinical application.

OBJECTIVES

The authors sought to explore the long-term effects of PRF on grafted fat and their optimal mixing ratio.

METHODS

Nude mice were randomly divided into a control group (receiving subcutaneous injection of fat granules) and 4 PRF groups (receiving subcutaneous injection of PRF and fat granules at volume ratios of 1:5, 1:10, 1:15, and 1:20, respectively). The graft samples (n = 12) were obtained in weeks 4, 8, and 12 to (1) calculate retention rates; (2) evaluate gene and protein expression of vascular endothelial growth factor A (VEGF-A), peroxisome proliferator-activated receptor-γ (PPAR-γ), type I collagen A1 (COL1-A1), and B-cell lymphoma-2 associated X protein (BAX); (3) perform hematoxylin and eosin, Masson's trichrome, α-smooth muscle action, and periplipin-1 stainings; and (4) count the microvessels and viable adipocytes.

RESULTS

Compared with the control group, PRF groups had higher retention rates, a higher gene/protein expression of VEGF-A, a lower gene/protein expression of COL1-A1 and BAX, less fibrosis, and more microvessels and viable adipocytes. Group 1:10 was superior to other groups in terms of retention rates and other evaluation indexes. The expression of PPAR-γ did not significantly differ among groups.

CONCLUSIONS

PRF may not play a long-term effect on adipogenesis, but it can still promote fat graft survival through facilitating vascularization, regulating collagen production, and inhibiting apoptosis. PRF can achieve the best promoting effect when the mixing ratio of PRF to fat is 1:10, which is recommended as the optimal ratio for clinical application.

Fat Processing Techniques: A Narrative Review

OBJECTIVE

This study reviewed the literature regarding different fat processing techniques, in order to update the information for healthcare personnel and provide the latest evidence in selecting purification methods.

METHODS

PubMed (MEDLINE), EMBASE, the Cochrane Library, and the Cochrane Central Register of Controlled Trials were comprehensively searched to identify studies that compared different fat purification methods for animal and human studies published through July 2020. Papers were screened using inclusion and exclusion criteria, and relative data were collected for review.

RESULTS

A total of 3292 studies were identified, of which 30 were included for review. The findings of existing clinical studies showed that the filtration and washing filtration methods performed better in the volume retention rate of adipose tissue. In terms of postoperative complications (fat necrosis, nodules, cysts, etc.), the incidence of complications of centrifugation is generally higher than that of other purification methods, while Telfa gauze and washing filtration system show better safety. More comparative studies are needed to draw conclusions about clinical efficacy and satisfaction. The existing basic science studies generally believe that centrifugation has no advantage in the integrity and metabolic activity of adipose tissue. However, there is no definite conclusion about the volume retention rate of grafts in animal experiments.

CONCLUSION

In recent years, studies on the cost-effectiveness of various purification methods have emerged, and the efficiency advantages of commercial systems have also been gradually reflected. In the future, the purification efficiency will be improved based on ensuring clinical efficacy, which will be translated into cost savings.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. 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 .