Quercetin May Improve Fat Graft Survival by Promoting Fat Browning Peripherally

Improving Fat Graft Survival Using Soluble Molecule Preconditioning

Fat grafting is widely used in plastic surgery to correct soft tissue deformities. A major limitation of this technique is the poor long-term volume retention of the injected fat due to tissue remodeling and adipocyte death. To address this issue, various optimizations of the grafting process have been proposed. This scoping review focuses on preclinical and clinical studies that investigated the impact of various classes of soluble molecules on fat grafting outcomes. Globally, we describe that these molecules can be classified as acting through three main mechanisms to improve graft retention: supporting adipogenesis, improving vascularization, and reducing oxidative stress. A variety of 18 molecules are discussed, including insulin, VEGF, deferoxamine, botulinum toxin A, apocynin, N-acetylcysteine, and melatonin. Many biomolecules have shown the potential to improve long-term outcomes of fat grafts through enhanced cell survival and higher volume retention. However, the variability between experimental protocols, as well as the scarcity of clinical studies, remain obstacles to clinical translation. In order to determine the best preconditioning method for fat grafts, future studies should focus on dosage optimization, more sustained delivery of the molecules, and the design of homogenous experimental protocols and specific clinical trials.

Cold-Induced Browning: A Novel Method to Improve the Retention Rate of Fat Graft

BACKGROUND

Autologous fat grafting is frequently used to heal soft-tissue defects. The key restriction that must be addressed is the poor transplant retention rate. Growing evidence has demonstrated that the browning of white adipose tissue enhances the survival of fat grafts. We hypothesized that cold-induced browning before transplantation may be a novel method to improve fat graft survival.

METHOD

Mice were kept in the 4 °C environment for 1 week, 2 weeks, and 3 weeks separately to detect whether different times of cold exposure could induce different numbers of beige adipocytes. Then, inguinal fat (roughly 150 mg) was collected and transferred. After post-graft weeks 4 and 12, the grafts were collected. The graft retention rate, histological morphology, vascularization, and browning were all assessed.

RESULTS

Mice inguinal fat showed enhanced beige adipose regeneration as the cold exposure (4 °C) time increased. Cold-induced browning resulted in greater retention, reduced fibrosis and necrosis, and improved angiogenesis at post-graft weeks 4 and 12. Simultaneously, few beige adipocytes were seen in grafts at post-graft weeks 4 and 12.

CONCLUSIONS

Cold-induced browning showed increased retention by promoting angiogenesis in a paracrine manner. Cold exposure of subcutaneous fat before transplantation may be a novel method to improve fat graft retention rate and retention quality.

NO LEVEL ASSIGNED

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Survival Mechanisms and Retention Strategies in Large-Volume Fat Grafting: A Comprehensive Review and Future Perspectives

INTRODUCTION

Large-volume fat grafting is emerging as a promising technique in plastic and reconstructive surgery. However, the unpredictable graft volume retention rate remains a critical challenge. To address this issue, we need a profound understanding of the survival mechanisms following large-volume fat transplantation. This review summarizes known survival mechanisms and strategies to enhance graft retention.

METHODS

This review comprehensively examines the current literature on the survival mechanisms and retention strategies in large-volume fat grafting. A thorough literature search was conducted using PubMed, Medline and Google Scholar databases, focusing on studies published from 2009 to 2023.

CONCLUSION

In the current research on fat survival mechanisms, few have focused on large-volume fat grafting. This review provides an overview of the survival mechanisms specific to large-volume fat grafting and identifies a survival pattern distinct from that of small-volume fat grafting. Additionally, we have summarized existing strategies to improve graft retention across five stages (harvesting, processing, enrichment, grafting and post-graft care), analyzed their advantages and disadvantages and identified some of the most promising strategies.

LEVEL OF EVIDENCE IV

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.

Transplantation of Cold-Stimulated Subcutaneous Adipose Tissue Improves Fat Retention and Recipient Metabolism

BACKGROUND

Induction of beige fat for grafting is an emerging transplantation strategy. However, safety concerns associated with pharmaceutical interventions limit its wider application. Moreover, because beige fat is a special type of fat with strong metabolic functions, its effect on the metabolism of recipients after grafting has not been explored in the plastic surgery domain.

OBJECTIVES

The aim of this study was to explore whether cold-induced inguinal white adipose tissue (iWAT) transplantation has a higher retention rate and beneficial effects on recipient metabolism.

METHODS

C57/BL6 mice were subjected to cold stimulation for 48 hours to induce the browning of iWAT and harvested immediately. Subsequently, each mouse received a transplant of 0.2 mL cold-induced iWAT or normal iWAT. Fat grafts and recipients' iWAT, epididymal adipose tissue, and brown adipose tissue were harvested at 8 weeks after operation. Immunofluorescence staining, real-time polymerase chain reaction, and western blot were used for histological and molecular analysis.

RESULTS

Cold-induced iWAT grafting had a higher mean [standard error of the mean] retention rate (67.33% [1.74%] vs 55.83% [2.94%], P < .01) and more satisfactory structural integrity than normal iWAT. Histological changes identified improved adipose tissue homeostasis after cold challenge, including abundant smaller adipocytes, higher levels of adipogenesis, angiogenesis, and proliferation, but lower levels of fibrosis. More importantly, cold-induced iWAT grafting suppressed the inflammation of epididymal adipose tissue caused by conventional fat grafting, and activated the glucose metabolism and thermogenic activity of recipients' adipose tissues.

CONCLUSIONS

Cold-induced iWAT grafting is an effective nonpharmacological intervention strategy to improve the retention rate and homeostasis of grafts. Furthermore, it improves the adverse effects caused by traditional fat grafting, while also conferring metabolic benefits.

Improved therapy for clear cell renal cell carcinoma: beta-hydroxybutyrate and quercetin target hypoxia-induced angiogenesis and multidrug resistance

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is a form of kidney cancer characterized by dysregulated angiogenesis and multidrug resistance. Hypoxia-induced tumor progression plays a crucial role in ccRCC pathogenesis. Beta-hydroxybutyrate (BHB) and quercetin (QCT) have shown potential in targeting angiogenesis and drug resistance in various cancer types. This study investigates the combined effects of BHB and QCT in hypoxia-induced Caki-1 cells.

METHODS

Caki-1 cells were subjected to normoxic and hypoxic conditions and treated with BHB, QCT, or a combination of both. Cell-viability was assessed using the MTT assay, and mRNA expression levels of key angiogenesis-related genes (HIF-1α/2α, VEGF, Ang-1, Ang-2, and MDR4) were quantified through real-time PCR during 24 and 48 h.

RESULTS

BHB and QCT treatments, either alone or in combination, significantly reduced cell-viability in Caki-1 cells (p < 0.05). Moreover, the combined therapy demonstrated a potential effect in downregulating the expression of angiogenesis-related genes and MDR4 in hypoxia-induced cells, with a marked reduction in HIF-1α/2α, VEGF, Ang-1, and MDR4 expression (p < 0.05). The expression of Ang-2 increases significantly in presence of BHB combined QCT treatment.

CONCLUSION

This study highlights the promising potential of a combination therapy involving BHB and QCT in mitigating angiogenesis and MDR4 expression in hypoxia-induced ccRCC cells. These findings support further investigation into the underlying mechanisms and warrant clinical studies to evaluate the therapeutic value of this combined treatment for ccRCC patients. This research provides new insights into addressing the challenges posed by angiogenesis and drug resistance in ccRCC.

Pyrroloquinoline Quinone (PQQ) Improves Long-term Survival of Fat Grafts by Alleviating Oxidative Stress and Promoting Angiogenesis During the Early Phase After Transplantation

BACKGROUND

Reducing absorption after autologous fat grafting is a current challenge. Pyrroloquinoline quinone (PQQ) is the strongest known catalyst of redox reactions, which can scavenge reactive oxygen species (ROS) and alleviate oxidative stress.

OBJECTIVES

The aim of this study was to establish an in vivo model of PQQ-assisted lipotransfer and clarify the role of PQQ in reducing oxidative stress, alleviating apoptosis, and promoting angiogenesis during the acute hypoxic phase after grafting. In addition the study was performed to assess whether this intervention would have a positive effect on the improvement of long-term volume retention.

METHODS

Different concentrations of PQQ (low: 10 μM, medium: 100 μM, and high: 1000 μM) were mixed with human adipose tissue and transplanted subcutaneously into nude mice. Meanwhile, a control group of phosphate-buffered saline in an equal volume to PQQ was set up. On the third day after grafting, whole mount fluorescence staining was applied to detect ROS, mitochondrial membrane potential (MMP), apoptosis, adipocyte activity, and angiogenesis. Graft volume retention rate and electron microscopic morphology were evaluated at the third month. Immunohistochemistry and polymerase chain reaction (PCR) were further employed to elucidate the mechanism of action of PQQ.

RESULTS

PQQ-assisted fat grafting improved the long-term volume retention, promoted the quality and viability of the adipose tissue, and reduced the level of fibrosis. The underlying mechanism of PQQ assisted in scavenging the accumulated ROS, restoring MMP, enhancing adipocyte viability, alleviating tissue apoptosis, and promoting timely angiogenesis during the hypoxia stress phase. The most effective concentration of PQQ was 100 μM. Immunohistochemistry and PCR experiments confirmed that PQQ reduced the expression of Bax and cytochrome c in the mitochondrial apoptotic pathway and increased the level of the antiapoptotic molecule Bcl-2.

CONCLUSIONS

PQQ could improve the long-term survival of adipocytes by alleviating hypoxic stress and promoting timely angiogenesis in the early phase following lipotransfer.

LEVEL OF EVIDENCE: 4

Molecular mechanism of Hedyotis Diffusae Herba in the treatment of lupus nephritis based on network pharmacology

Aims: To determine the bioactive components of Hedyotis Diffusae Herba (HDH) and the targets in treating lupus nephritis (LN), and so as to elucidate the protective mechanism of HDH against LN. Methods and results: An aggregate of 147 drug targets and 162 LN targets were obtained from online databases, with 23 overlapped targets being determined as potential therapeutic targets of HDH against LN. Through centrality analysis, TNF, VEGFA and JUN were screened as core targets. And the bindings of TNF with stigmasterol, TNF with quercetin, and VEGFA with quercetin were further validated by molecular docking. By conducting Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses for drug targets, disease targets and the shared targets, TNF signaling pathway, Toll-like receptor signaling pathway, NF-kappa B signaling pathway and HIF-1 signaling pathway, etc., were found in all these three lists, indicating the potential mechanism of HDH in the treatment of LN. Conclusion: HDH may ameliorate the renal injury in LN by targeting multi-targets and multi-pathways, including TNF signaling pathway, NF-kappa B signaling pathway, HIF-1 signaling pathway and so on, which provided novel insights into further researches of the drug discovery in LN.