Adenosine-Prefabricated Adipose Tissue Improves Fat Graft Survival by Promoting VEGF-Dependent Angiogenesis

Dual Network Hydrogels Based on PRP and SA Promote the Retention Rate and Vascularization of Transplanted Fat

BACKGROUND

Autologous adipose tissue often experiences ischemia and hypoxia after transplantation, leading to low retention rates and unstable operative impacts due to necrotic absorption. Platelet-rich plasma (PRP) can enhance fat regeneration and increase the fat retention rate after transplantation. However, the quick release of growth factors (GFs) in PRP decreases therapeutic efficiency. This study aimed to achieve a slow release of PRP to promote fat retention.

METHODS

We prepared a dual-network hydrogel (DN gel) based on FDA-approved PRP and sodium alginate (SA) through a simple "one-step" activation process. In vivo study, adipose tissue with saline (control group), SA gel (SA gel group), PRP gel (PRP gel group), and DN gel (DN gel group) was injected subcutaneously into the dorsum of nude mice. At 4 and 12 weeks after injection, tissues were assessed for volume and weight. Hematoxylin and eosin staining (HE) and immunofluorescence staining were performed for histological assessment.

RESULTS

DN gel exhibits long-lasting growth factor effects, surpassing conventional clinical PRP gel regarding vascularization potential. In fat transplantation experiments, DN gel demonstrated improved vascularization of transplanted fat and increased retention rates, showing promise for clinical applications.

CONCLUSIONS

DN gel-assisted lipofilling can significantly improve the retention rate and quality of transplanted fat. DN gel-assisted lipofilling, which is considered convenient, is a promising technique to improve neovascularization and fat survival.

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Modern and Non-Invasive Methods of Fat Removal

Adipocytes accumulate triacylglycerols as an energy store, thereby causing an increase in the adipose tissue volume. Weight gain can be prevented through damage to the adipocyte structure or an increase in the body's metabolic rate. Commonly used methods to disintegrate the cell membrane of adipocytes include injection lipolysis, cryolipolysis, ultrasonic lipolysis, radiofrequency lipolysis, laser lipolysis, carboxytherapy, and lipolysis using an electromagnetic field. The names of these methods suggest which substances are being used, and their main advantages are a very low invasiveness, as well as effectiveness. However, new discoveries in medicine, along with individuals' desire to improve their appearance, have resulted in numerous studies on more ways of reducing body fat. Great potential is seen in beige adipocytes, which can be transformed, i.e., "recruited" from white adipocytes, or synthesized de novo; they also show thermogenic properties. One of the stimuli inducing the formation of beige adipocytes is cold and B3-adrenergic stimulation. Based on these findings, the researchers created, for example, cooling clothing. Additionally, curcumin and natural anthocyanins have proven to be helpful in the treatment of obesity and diabetes, by stimulating the secretion of glucagon-like peptide-1, and inducing the formation of beige adipocytes. Another study showed that the conversion of white adipose tissue is indirectly influenced by interleukin-6 secreted by the muscles, the expression of which is increased in people actively exercising. Moreover, there is potential in adenosine analogs, fenoldopam, rhubarb, the herbal extract Ephedra sinica Stapf, electroacupuncture simulation, and the drug CBL-514. Despite knowledge and experience, the ideal method for a quick and noticeable, but safe and non-invasive reduction of body fat has not been found yet. The research conducted nowadays may bring us closer to the development of a universal method, and turn out to be a breakthrough in the fight against overweight and obesity.

Mechanical Stress Improves Fat Graft Survival by Promoting Adipose-Derived Stem Cells Proliferation

Cell-assisted lipotransfer (CAL), defined as co-transplantation of aspirated fat with enrichment of adipose-derived stem cells (ASCs), is a novel technique for cosmetic and reconstructive surgery to overcome the low survival rate of traditional fat grafting. However, clinically approved techniques for increasing the potency of ASCs in CAL have not been developed yet. As a more clinically applicable method, we used mechanical stress to reinforce the potency of ASCs. Mechanical stress was applied to the inguinal fat pad by needling. Morphological and cellular changes in adipose tissues were examined by flow cytometric analysis 1, 3, 5, and 7 days after the procedure. The proliferation and adipogenesis potencies of ASCs were evaluated. CAL with ASCs treated with mechanical stress or sham control were performed, and engraftment was determined at 4 weeks post-operation. Flow cytometry analysis revealed that mechanical stress significantly increased the number as well as the frequency of ASC proliferation in fat. Proliferation assays and adipocyte-specific marker gene analysis revealed that mechanical stress promoted proliferation potential but did not affect the differentiation capacity of ASCs. Moreover, CAL with cells derived from mechanical stress-treated fat increased the engraftment. Our results indicate that mechanical stress may be a simple method for improving the efficacy of CAL by enhancing the proliferation potency of ASCs.