Cell-Assisted Lipotransfer: A Systematic Review of Its Efficacy

Micro/Nanobubble-Assisted Lipotransfer: In Vivo Evidence of Improved Graft Outcomes

OBJECTIVE

Retention rates of lipotransfer remain variable, with the underlying cause associated with tissue oxygenation and blood supply barriers. One promising new method of improving tissue oxygenation is micro/nanobubbles (MNBs), which are small gas bubbles (<100 μm) generated within a saline solution. MNBs are stable and carry a significant amount of oxygen, and because of their negatively charged surface characteristics, they are an ideal oxygen-delivery solution. Thus, we hypothesize that washing/oxygenating lipoaspirate tissue prior to transplantation in a micro/nanobubble saline solution will improve graft survival and quality compared to a saline control.

METHODS

Human lipoaspirate samples obtained from healthy donors were washed with an oxygenated MNB or saline wash. These samples were then injected into the dorsum of sixteen 6-week-old male BALB/c mice, where each mouse received one saline and one MNB-washed graft. At 2-, 4-, 8-, and 12-week time points, the explants were harvested and weighed, and gas pycnometry was performed to assess graft volume. The tissues were also subjected to hematoxylin and eosin (HE) staining and immunohistochemistry to detect perilipin and blood vessels (CD31). These stains, as well as adipocyte count and area quantifications, were analyzed using ImageJ.

RESULTS

HE staining revealed that the control group demonstrated notable adipocyte hypertrophy, while MNB-washed samples had evident adipocyte hyperplasia. This observation was confirmed by an analysis of variance (ANOVA), which showed that the control group had a larger average graft mass and volume (P < 0.01). MNB-washed grafts also exhibited significantly greater adipocyte counts and smaller adipocytes (P < 0.001). Perilipin staining was also greater in the MNB group at the 2- and 4-week time point indicating improved de novo adipogenesis following implantation. Lastly, CD31 staining revealed a significantly greater core vessel density and angiogenesis at the 4-week and 12-week time points (P < 0.01).

CONCLUSIONS

Our study demonstrates that MNBs enhance tissue quality as indicated by a significant increase in de novo adipogenesis, higher vessel density, and decreased adipocyte hypertrophy. Additional studies are needed to evaluate the clinical effectiveness. Nevertheless, incorporating MNBs into procedures holds great promise in tackling the ongoing challenge of inconsistent outcomes in lipotransfer.

Autologous fat grafting auxiliary methods in craniofacial deformities: A systematic review and network meta-analysis

BACKGROUND

To increase autologous fat grafting (AFG) volume retention, current advancements focus on adding an auxiliary method to the process. This review aimed to address which auxiliary methods prove to be the best in terms of volume retention outcome.

METHODS

A comprehensive literature search was performed in five medical databases, including PubMed, Proquest, Scopus, CENTRAL, and ScienceDirect, until March 2024, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines.

RESULTS

Twenty-six studies were included in this review, and seven studies were included in the network meta-analysis. Reported auxiliary methods include stromal vascular fractions (SVFs) [12.20, 95% confidence intervals (CI) 0.04 to 24.35], adipose tissue-derived stem cells (ADSCs) (24.20, 95% CI 4.14 to 44.26), and platelet-rich plasma (PRP) [24.10, 95% CI -2.68 to 50.88]. When compared with the standard AFG approach, SVFs (p = 0.049) and ADSCs (p = 0.018) were more successful in retaining volume. However, PRP (p = 0.077) was not as effective. The comparison between auxiliary approaches, ADSCs vs PRP (p = 0.994), ADSCs vs SVFs (p = 0.271), and PRP vs SVF (p = 0.383), did not show any significant differences. Subgroup analysis revealed that the use of volumetric measuring methods has a substantial impact on the reported volume retention (p < 0.0001).

CONCLUSION

Enhanced volume retention can be attained with the utilization of SVF and ADSCs auxiliary methods in comparison to AFG, with or without PRP. Given the insignificant differences between SVF and ADSC, along with the greater complexity of the ADSC process, we recommend for the preferable use of SVF.

Flap-Free Tendon Coverage Using Autologous Fat Grafts Enhanced with Platelet-Rich Plasma and Growth Factors at a Secondary Level Hospital: A Case Report

BACKGROUND

Autologous fat grafting, enriched with platelet-rich plasma (PRP), has been established as an effective and affordable treatment for various types of wound healing. However, its efficacy in managing wounds with tendon exposure has not been thoroughly investigated.

METHODS

We report the case of a 40-year-old male who sustained a severe friction burn on his hand and forearm from a car accident, resulting in significant tissue loss and exposed extensor tendons.

RESULTS

Traditional wound treatment strategies were not implemented due to specific patient circumstances. After initial surgical management failed to prevent necrosis and maintain coverage of the exposed tendons, the patient underwent a novel treatment involving autologous fat grafting combined with PRP and growth factors. The procedure was repeated twice within a month to promote granular tissue formation over that area and facilitate subsequent coverage with an epidermoreticular graft. By day 21 post-initial graft, the exposed tendons were 98% covered with granular tissue. Complete wound coverage was achieved by day 60, and by day 130 the patient had regained 90% functionality of the affected limbs.

CONCLUSIONS

This case illustrates the potential of autologous fat grafting combined with PRP and growth factors as a viable, flap-free alternative for covering tendon exposures. This approach not only enhances wound healing but also supports functional recovery, underscoring the need for further research into its broader applicative potentials.

Comparative Efficacy and Safety of Cell-Assisted and Conventional Lipotransfer in Facial Filling: A Systematic Review and Meta-Analysis

PURPOSE

We aim to compare the efficacy and safety of cell-assisted lipotransfer (CAL) and conventional lipotransfer (CLT) in facial filling.

METHODS

The PubMed and Embase databases were searched for relevant publications until February 2023. All studies evaluating the efficacy and safety of cell-assisted and conventional lipotransfer in facial filling were included. We calculated pooled standardized mean difference (SMD) and 95% CIs for continuous outcomes and pooled risk ratio (RR) with 95% CIs for binary outcomes. The Cochrane's Risk of Bias Tool and the Newcastle-Ottawa Scale (NOS) were used to evaluate the quality of studies.

RESULTS

A total of 15 studies with 737 patients were included in this analysis. The fat survival rate and patient satisfaction rate were significantly higher in the CAL group compared to the CLT group (SMD: 3.04, 95% CI 2.09-3.99; RR: 1.34, 95% CI 1.08-1.67). However, no significant difference in complication rates (RR: 0.95, 95% CI 0.50-1.81) and a lower secondary operation rate in the CAL group (RR: 0.52, 95% CI 0.03-0.82) were observed. No obvious publication bias was observed in the funnel plot (Egger's P values = 0.084 and 0.403).

CONCLUSIONS

Based on the pooled results, we tentatively conclude that CAL may have superior fat survival rate and satisfaction rate compared to CLT in facial filling, without compromising patient safety. However, the majority of the included studies were observational studies with small sample sizes. Future research should focus on investigating the long-term efficacy and safety of these techniques.

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 .

Exosomes from Adipose-Tissue-Derived Stem Cells Induce Proapoptotic Gene Expression in Breast Tumor Cell Line

Lipofilling is an option for breast reconstruction after tumor resection to avoid the complications of an implant-based reconstruction. Although some concerns exist regarding the oncological safety of tissue rich in mesenchymal stem cells with their proangiogenic and proliferation-supportive properties, there are also reports that adipose-tissue-derived stem cells can exhibit antitumoral properties. We isolated primary adipose-tissue-derived stem cells. Both conditioned medium and exosomes were harvested from the cell culture and used to treat the breast cancer cell line MCF-7. Cell viability, cytotoxicity, and gene expression of MCF-7 cells in response to the indirect co-culture were evaluated. MCF-7 cells incubated with exosomes from adipose-tissue-derived stem cells show reduced cell viability in comparison to MCF-7 cells incubated with adipose-tissue-derived stem-cell-conditioned medium. Expression of proapoptotic genes was upregulated, and expression of antiapoptotic genes was downregulated. The debate about the oncological safety of autologous fat grafting after tumor resection continues. Here, we show that exosomes from adipose-tissue-derived stem cells exhibit some antitumoral properties on breast cancer cell line MCF-7.

Lipotranferences in post neurosurgical esthetic defects

Background

There are numerous procedures in which, beyond adequate manipulation of the temporalis muscle and cranial closure, patients may present bone and muscle defects due to atrophy and consequent facial asymmetry, causing psychological discomfort and functional deterioration. The objective of our work is to combine the knowledge of plastic surgery and apply it to cranial reconstructions with fat transfers in post-neurosurgical patients, analyzing its results.

Methods

During the year 2022, 45 fat transfer procedures were performed for the correction of craniofacial defects, of which 29 were female and 16 were male. All had a surgical history of pterional craniotomies and their variants, orbitozygomatic and transzygomatic approaches, with the consequent volume deficit.

Results

The procedure was performed on an outpatient basis, with local anesthesia, and in an average time of 30-40 min. The lower hemiabdominal region was used as the donor area, processing the fat using the decantation technique and injecting it into the receptor area at the craniofacial level. The patients tolerated the procedure adequately without intraoperative complications or superadded events.

Conclusion

Fat transfer is a minimally invasive, effective, and cost-effective technique that plastic surgery offers us to implement in post-neurosurgical patients, as it achieves natural results that stand the test of time.

Successful fat-only whole breast reconstruction using cultured mature adipocytes and conditioned medium containing MCP-1

A mastectomy is a curative treatment for breast cancer. It causes breast and soft tissue deficits, resulting in a chest with poor vascularity. Autologous tissue breast reconstruction is commonly associated with donor site morbidity. Breast implants are another reconstruction alternative, but they are associated with infection, rupture, and the need for replacement. Autologous aspirated fat grafting has appeared as an ideal breast reconstruction method, but low graft viability and high resorption remain as the main shortcomings. We developed a novel method for fat-only grafts using cultured mature adipocytes (CMAs) mixed with their condition medium. Twenty-five mastectomy patients, aged 32-72 years, received a mixed grafting of CMAs, MCP1-containing condition medium, and fat grafts for total breast reconstruction. In follow-up periods of 24-75 months, MRI analysis showed full thickness fat-engraftment. The cell proliferation marker Ki67 was negative in post-transplant biopsy specimens from all patients. Aesthetic full breast morphology was achieved, patient satisfaction was evaluated 1 year and 3-6 years after surgery. All grafts were confirmed safe, demonstrating high reliability and long-term sustainability.

Three-Dimensional Bioprinting in Soft Tissue Engineering for Plastic and Reconstructive Surgery

Skeletal muscle tissue engineering (TE) and adipose tissue engineering have undergone significant progress in recent years. This review focuses on the key findings in these areas, particularly highlighting the integration of 3D bioprinting techniques to overcome challenges and enhance tissue regeneration. In skeletal muscle TE, 3D bioprinting enables the precise replication of muscle architecture. This addresses the need for the parallel alignment of cells and proper innervation. Satellite cells (SCs) and mesenchymal stem cells (MSCs) have been utilized, along with co-cultivation strategies for vascularization and innervation. Therefore, various printing methods and materials, including decellularized extracellular matrix (dECM), have been explored. Similarly, in adipose tissue engineering, 3D bioprinting has been employed to overcome the challenge of vascularization; addressing this challenge is vital for graft survival. Decellularized adipose tissue and biomimetic scaffolds have been used as biological inks, along with adipose-derived stem cells (ADSCs), to enhance graft survival. The integration of dECM and alginate bioinks has demonstrated improved adipocyte maturation and differentiation. These findings highlight the potential of 3D bioprinting techniques in skeletal muscle and adipose tissue engineering. By integrating specific cell types, biomaterials, and printing methods, significant progress has been made in tissue regeneration. However, challenges such as fabricating larger constructs, translating findings to human models, and obtaining regulatory approvals for cellular therapies remain to be addressed. Nonetheless, these advancements underscore the transformative impact of 3D bioprinting in tissue engineering research and its potential for future clinical applications.

Extracellular Vesicles Derived From Hypoxia-Treated Human Adipose Stem Cells Increase Proliferation and Angiogenic Differentiation in Human Adipose Stem Cells

BACKGROUND

Adipose-derived stem cells (ADSCs) are crucial in cell-assisted lipotransfer (CAL). ADSC-derived exosomes could improve the survival of CAL. Almost all relevant research now ignores ADSCs in favor of studying the proangiogenic potential of extracellular vesicles (EVs) on human umbilical vein endothelial cells (HUVECs).

OBJECTIVES

Given the significance of ADSCs in CAL, the authors sought to verify that EVs from ADSCs under hypoxia treatment can enhance the angiogenic potential of ADSCs.

METHODS

EVs were harvested from human ADSCs (hADSCs) under normoxia and hypoxia. A Cell Counting Kit-8 (CCK-8) assay was used to measure the proliferation of hADSCs. By examining the expression of CD31, vascular endothelial growth factor receptor 2, and vascular endothelial growth factor, the pro-angiogenic differentiation potential was assessed. Moreover, a tube formation experiment was carried out to evaluate the pro-angiogenic differentiation potential.

RESULTS

Hypoxic EVs showed more significant pro-proliferative and pro-angiogenic potential. Angiogenesis was more vigorous in hADSCs treated with hypoxic EVs than in those treated with nomorxic EVs. The hADSCs treated with hypoxic EVs expressed higher angiogenic markers, according to real-time polymerase chain reaction (RT-PCR) and Western blot analysis, which revealed more angiogenic marker expression in hypoxic EV-treated hADSCs. The same result was demonstrated by tube formation on Matrigel in vitro.

CONCLUSIONS

Hypoxic EVs significantly increased the proliferation and angiogenic differentiation potential of hADSCs. Hypoxic EV-treated ADSCs may be beneficial to CAL and prevascularized tissue-engineered constructs.

Disturbances of the stomatognathic system and possibilities of its correction in patients with craniofacial morphea

Morphea en coup de sabre and progressive hemifacial atrophy are extremely rare connective tissue disorders causing facial deformity. In extreme cases, morphological disorders are accompanied by symptoms of a clear impairment of the stomatognathic system. The aetiology of the above-mentioned diseases is still unknown. Properly planned therapy in the field of maxillofacial orthopaedics makes it possible to correct the asymmetric pattern of hard tissue growth and thus enable rehabilitation. The task of augmentation techniques is the volumetric supplementation of tissue defects resulting from atrophic processes. The degree of destruction and the extent of changes determine the method of correction. Mild and moderate defects are treated mainly with biomaterials and autologous adipose tissue. The severe course of hemifacial atrophy and morphea en coup de sabre and the associated significant tissue atrophy necessitate the search for more complex methods of treatment. In this paper, we summarize the disturbances of the stomatognathic system in patients with craniofacial morphea, together with an analysis of current treatment options.

Exosomes Derived from Human Adipose-Derived Stem Cells Cannot Distinctively Promote Graft Survival in Cryopreservation Fat Grafting

BACKGROUND

Cryopreserved fat has limited clinical applications due to its rapid absorption, high degree of fibrosis, and risk of complications after grafting. Many studies have verified that Adipose-derived mesenchymal stem cell-derived exosomes (ADSC-Exos) can improve fresh fat graft survival. This study assessed whether ADSC-Exos could improve the survival of cryopreserved fat grafts.

METHODS

Exosomes were isolated from human ADSCs were subcutaneously engrafted with adipose tissues stored under different conditions (fresh; cryopreserved for 1 month) into the backs of BALB/c nude mice (n = 24), and exosomes or PBS were administered weekly. Grafts were harvested at 1, 2, 4, and 8 weeks, and fat retention rate, histologic, and immunohistochemical analyses were conducted.

RESULTS

At 1, 2, and 4 weeks after the transfer, cryopreserved fat grafts in groups of exosome-treated showed better fat integrity, fewer oil cysts, and reduced fibrosis. Further investigations of macrophage infiltration and neovascularization revealed that those exosomes increased the number of M2 macrophages at 2 and 4 weeks (p<0.05), but had limited impact on vascularization (p>0.05). It's important to note that no significant differences (p>0.05) were observed between the two groups in both histological and immunohistochemical evaluations at 8 weeks post-transplantation.

CONCLUSIONS

This study suggests that ADSC-Exos could improve the survival of cryopreserved fat grafts in the short term (within 4 weeks), but the overall improvement was poor (after 8 weeks). This suggests that the utility of using ADSC-Exos to treat cryopreserved adipose tissue grafts is limited.

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 .

Three-Dimensional Volumetric Analysis of the Effect of Interval Time in Autologous Fat Graft Breast Augmentation

BACKGROUND

Autologous adipose tissue has become increasingly popular in cosmetic and plastic reconstructive surgery, especially breast augmentation surgery. However, the volume retention rate after transplantation significantly varies and may be unsatisfactory. Many patients need two or more autologous fat graft breast augmentations to achieve the expected effect. There are currently no studies on optimal timing between fat injections.

METHODS

We identified target patients with secondary or multiple autologous fat transplantations by inclusion and exclusion criteria and used three-dimensional scanning technology to calculate the volume retention. Patients were divided into two groups according to the dates of the first and second operations (group A: interoperative time < 120 days, group B: interoperative time ≥ 120 days). We used SPSS 26 for statistical calculations.

RESULTS

We included 161 patients in this retrospective study, with an average volume retention rate of 36.56% in group A (n = 85) and 27.45% in group B (n = 76). The independent sample t test showed that the volume retention rate in group A was higher than that in group B (P < 0.001). And the paired t test showed there is a significant improvement of volume retention rate after the second fat graft session (P < 0.001). Multivariate regression analysis showed that the interval time was an independent factor affecting the postoperative volume retention rate.

CONCLUSION

The interval time between autologous fat transplantation for augmentation mammaplasty was an independent factor affecting the postoperative volume retention rate. The postoperative volume retention rate of the < 120 days group was higher than that of the ≥ 120 days group.

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 .

Delayed Supplementation Strategy of Extracellular Vesicles from Adipose-Derived Mesenchymal Stromal Cells with Improved Proregenerative Efficiency in a Fat Transplantation Model

Background

Mesenchymal stromal cells (MSCs) and their secreted extracellular vesicles (MSC-EVs) possess similar proregenerative effects when injected into defects immediately following trauma. However, MSC-EVs are superior to MSCs in terms of storage and rejection reflection, while immediate administration of MSC-EVs is related to several target cells for most donor cells die within few weeks. Besides, the inflammatory cascade is incited, providing an unfavorable environment for target cells. We hypothesized that delayed injection of MSC-EVs might have priority on tissue regeneration than instant injection.

Method

Extracellular vesicles isolated from adipose-derived mesenchymal stromal cells (ADSC-EVs) were administered into human umbilical vein endothelial cells (HUVECs) in vitro at different doses. The migration of HUVECs was assessed using the scratch wound healing assay, whereas the length of tubes and number of vessel-like structures formed by HUVECs were determined using tube formation assay. Next, 24 BALB/c nude mice were randomly divided into three groups (n = 8). For the EV-delayed group, ADSC-EVs were injected into transplanted fat a week later than the EV-immediate group. The volume and weight of grafts were measured at 3 months after fat transplantation. Further, the number of CD31-possitive vessels and CD206-possitive cells in the fat grafts was quantified.

Results

Compared with the EV-immediate group, the EV-delayed group had a higher fat tissue retention volume (0.11 ± 0.02 mL versus 0.08 ± 0.01 mL), more neovessels (31.00 ± 4.60 versus 24.20 ± 3.97), and fewer cysts. Furthermore, there were more Ki67-positive cells (25.40 ± 7.14 versus 16.20 ± 4.17) and CD206-positive M2 macrophages cells (23.60 ± 3.44 versus 14.00 ± 3.85) in the EV-delayed group than in the EV-immediate group.

Conclusion

Delayed injection of ADSC-EVs promotes fat graft volume retention by stimulating angiogenesis. These findings suggest that delayed supplementation might be a more effective strategy for the application of MSC-EVs in tissue regeneration.

Human Adipose Mesenchymal Stromal/Stem Cells Improve Fat Transplantation Performance

The resorption rate of autologous fat transfer (AFT) is 40–60% of the implanted tissue, requiring new surgical strategies for tissue reconstruction. We previously demonstrated in a rabbit model that AFT may be empowered by adipose-derived mesenchymal stromal/stem cells (AD-MSCs), which improve graft persistence by exerting proangiogenic/anti-inflammatory effects. However, their fate after implantation requires more investigation. We report a xenograft model of adipose tissue engineering in which NOD/SCID mice underwent AFT with/without human autologous AD-MSCs and were monitored for 180 days (d). The effect of AD-MSCs on AFT grafting was also monitored by evaluating the expression of CD31 and F4/80 markers. Green fluorescent protein-positive AD-MSCs (AD-MSC-GFP) were detected in fibroblastoid cells 7 days after transplantation and in mature adipocytes at 60 days, indicating both persistence and differentiation of the implanted cells. This evidence also correlated with the persistence of a higher graft weight in AFT-AD-MSC compared to AFT alone treated mice. An observation up to 180 d revealed a lower resorption rate and reduced lipidic cyst formation in the AFT-AD-MSC group, suggesting a long-term action of AD-MSCs in support of AFT performance and an anti-inflammatory/proangiogenic activity. Together, these data indicate the protective role of adipose progenitors in autologous AFT tissue resorption.

Research Progress on Preparation, Mechanism, and Clinical Application of Nanofat

Autologous adipose tissue is an ideal soft tissue filling material in theory, which has the advantages of easy access, comprehensive source, and high biocompatibility and is now widely used in clinical practice. Based on the above benefits of autologous fat, autologous fat grafting is an essential technique in plastic surgery. Conventional macrofat is used to improve structural changes after soft tissue damage or loss caused by various causes such as disease, trauma, or aging. Due to the large diameter of particles and to avoid serious complications such as fat embolism, blunt needles with larger diameters (2 mm) are required, making the macrofat grafting difficult to the deep dermis and subdermis. Nanofat grafting is a relatively new technology that has gained popularity in cosmetic surgery in recent years. Nanofat is produced by mechanical shuffling and filtration of microfat, which is harvested by liposuction. The harvesting and processing of nanofat are cost-effective as it does not require additional equipment or culture time. Unlike microfat, nanofat particles are too small to provide a notable volumizing effect. Studies have shown that nanofat contains abundant stromal vascular fraction cells and adipose-derived stem cells, which help reconstruct dermal support structures, such as collagen, and regenerate healthier, younger-looking skin. Moreover, the fluid consistency of nanofat allows application in tissue regeneration, such as scars, chronic wounds, and facial rejuvenation. This article reviews the current research progress on the preparation, mechanism, and clinical application of nanofat.

Improving Fat Transplantation Survival and Vascularization with Adenovirus E4+ Endothelial Cell-Assisted Lipotransfer

Autologous fat transplantation is plagued by an unpredictable and often significant degree of graft loss. AdE4+ endothelial cells (ECs) are human endothelial cells that have been transduced with the E4ORF1 region of human adenovirus type 5, resulting in long-term preservation of EC proliferation and angiogenic capability without immortalization. We hypothesized that AdE4+ EC-enriched fat grafts would demonstrate improved volume retention secondary to enhanced angiogenesis. Three experimental groups were prepared by admixing 400 µL of patient lipoaspirate with 100 µL of AdE4+ EC suspensions (high AdE4+ EC concentration-enriched [5 × 106/mL], low AdE4+ EC concentration-enriched [1.25 × 106/mL], or PBS) and injected subcutaneously into the bilateral dorsa of nude mice. Fat transplants were explanted at 90 and 180 days for volumetric and histologic analyses. After both 90 and 180 days, AdE4+ EC-enriched fat grafts showed greater mean volume preservation compared to control grafts (p < 0.05). Regions of focal necrosis were only noticed in low AdE4+ EC concentration-enriched and control groups after 180 days. Histologic analysis demonstrated the presence of healthy adipocytes in all AdE4+ EC-enriched fat grafts in which both human and host ECs were evident after 90 and 180 days. AdE4+ EC enrichment improved fat graft volume preservation and vascularization in this murine xenograft model. Though further study is warranted, AdE4+ ECs demonstrated to be promising as a potential off-the-shelf adjunct for improving the volume, quality, and consistency of fat engraftment.

Preoperative Short-Term High Carbohydrate Diet Provides More High-Quality Transplantable Fat and Improves the Outcome of Fat Grafts in Mice

BACKGROUND

Patients with a low body mass index may have inadequate high-quality adipose tissue for transplantation. The influence of high-energy diets on adipose tissue and graft retention remains unknown.

OBJECTIVES

We explored inguinal fat pad alternation in mice fed on a short-time high-fat diet (HFD) or a high-carbohydrate diet (HCD) preoperatively and the morphological and histological differences after transplantation.

METHODS

Mice were fed HFD (60% kilocalories from fat, 20% from carbohydrate), HCD (9.3% kilocalories from fat, 80.1% from carbohydrate), or normal (12% kilocalories from fat, 67% kilocalories from carbohydrate) diets for 2 or 4 weeks. Histological analyses were carried out following hematoxylin and eosin staining, and CD34 and proliferating cell nuclear antigen immunostaining. The uncoupling protein-1 (UCP-1) expression was determined by western blotting. Fat pads from each group were grafted into the dorsal region of the recipient mice and morphological and histological changes were determined 4, 8, and 12 weeks post-transplantation. Vascular endothelial growth factor α and platelet-derived growth factor α expression were determined using quantitative polymerase chain reaction.

RESULTS

The inguinal fat pad volume increased in the HFD and HCD groups. The presence of multilocular adipocytes in inguinal fat of HCD-fed mice, combined with the increased UCP-1 content, suggested adipocyte browning. HCD grafts showed higher volume retention and reduced oil cyst formation, possibly attributed to better angiogenesis and adipogenesis.

CONCLUSIONS

HCD enlarged adipose tissue and improved grafts survival rates, which may be due to the browning of fat before grafting and enhanced angiogenesis after grafting.

Cell-Assisted Lipotransfer in Breast Augmentation Surgery: Clinical Outcomes and Considerations for Future Research

Autologous fat transfer is a widely used surgical technique, chosen by numerous plastic surgeons for breast augmentation surgery. This technique is based on three steps: 1. harvesting of the lipoaspirate from the patient, 2. centrifugation and removal of the top, oily, layer, and 3. implantation in the patient’s breast(s). It has been associated with various complications, including post-surgical fat resorption, as measured quantitatively with MRI, CT, and other 3D-quantification systems.

Adipose-derived stem cells have been explored as a means of addressing fat resorption. They can be separated from the lipoaspirate following centrifugation, and enzymatically purified from unwanted debris, with collagenase, forming the stromal vascular fraction. The stromal vascular fraction is then recombined with the graft volume prior to implantation. This novel technique, referred to as “cell-assisted lipotransfer”, has shown promising results in terms of reducing fat resorption. These results are due to the pro-angiogenic and pro-adipogenic ability of the stem cells, which allow the graft to address the conditions of ischemia more effectively than autologous fat transfer.

The aim of this review is to explore the ways in which cell-assisted lipotransfer is different from the autologous fat transfer, as well as how and why adipose-derived stem cells may contribute towards limiting fat resorption. The immunological background of these cells is discussed in detail, while grounds for further development are discussed, by means of the administration of external growth factors, which could, potentially, maximize outcomes, while limiting complications.

Improving Low-Density Fat by Condensing Cellular and Collagen Content through a Mechanical Process: Basic Research and Clinical Applications

BACKGROUND

Large-volume fat grafting results in high absorption and complication rates. Low-density fat includes small numbers of viable cells and considerable oil, resulting in nodules and oil cysts. This study evaluated a strategy for large-volume fat grafting using a mechanical process to condense low-density fat and transplanting it with high-density fat.

METHODS

Low-density fat, defined as the upper half of centrifuged lipoaspirates, was emulsified by intersyringe shifting and centrifuged to obtain condensed low-density fat. Fresh condensed low-density fat was analyzed by counting cells in the stromal vascular fraction, and by electron scanning and Western blotting. The retention rate and histologic changes of the product were analyzed using a fat grafting model in nude mice. Transplantation with a combination of condensed low-density fat and high-density fat was tested in patients undergoing breast reconstruction and breast augmentation.

RESULTS

The condensed low-density fat derived from low-density fat contained a large number of stromal vascular fraction cells and collagens, comparable to that of high-density fat and much higher than in low-density fat and Coleman fat. Retention rates 12 weeks after transplantation were higher for condensed low-density fat (55.0 ± 7.5 percent) than for low-density fat (31.1 ± 5.7 percent) and Coleman fat (41.1 ± 6.8 percent), with condensed low-density fat having fewer oil cysts and lower macrophage infiltration. Patients grafted with combined condensed low-density fat and high-density fat showed good long-term volume retention.

CONCLUSIONS

Using mechanical methods to condense low-density fat to a level comparable to that of high-density fat is a practical method of improving fat graft retention and avoiding severe complications. This new strategy may improve the quality of lipoaspirates for patients requiring large-volume augmentation.

Characterized the Adipogenic Capacity of Adipose-Derived Stem Cell, Extracellular Matrix, and Microenvironment With Fat Components Grafting

Background: Autologous fat grafting has been a widely used technique; however, the role of adipose-derived stem cells (ASCs), extracellular matrix (ECM), and microenvironment in fat regeneration are not fully understood. Methods: Lipoaspirates were obtained and processed by inter-syringe shifting to remove adipocytes, yielding an adipocyte-free fat (Aff). Aff was then exposed to lethal dose of radiation to obtain decellularized fat (Df). To further remove microenvironment, Df was rinsed with phosphate-buffered saline (PBS) yielding rinsed decellularized fat (Rdf). Green fluorescent protein (GFP) lentivirus (LV-GFP)-transfected ASCs were added to Df to generate cell-recombinant decellularized fat (Crdf). Grafts were transplanted subcutaneously into nude mice and harvested over 3 months. Results: Removal of adipocytes (Aff) didn't compromise the retention of fat grafts, while additional removal of stromal vascular fraction (SVF) cells (Df) and microenvironment (Rdf) resulted in poor retention by day 90 (Aff, 82 ± 7.1% vs. Df, 28 ± 6.3%; p < 0.05; vs. Rdf, 5 ± 1.2%; p < 0.05). Addition of ASCs to Df (Crdf) partially restored its regenerative potential. Aff and Crdf exhibited rapid angiogenesis and M2-polarized macrophages infiltration, in contrast to impaired angiogenesis and M1-polarized inflammatory pattern in Df. GFP + ASCs participated in angiogenesis and displayed a phenotype of endothelial cells in Crdf. Conclusion: Adipose ECM and microenvironment have the capacity to stimulate early adipogenesis while ECM alone cannot induce adipogenesis in vivo. By directly differentiating into endothelial cells and regulating macrophage polarization, ASCs coordinate early adipogenesis with angiogenesis and tissue remodeling, leading to better long-term retention and greater tissue integrity.

Update on the Basic Science Concepts and Applications of Adipose-Derived Stem Cells in Hand and Craniofacial Surgery

SUMMARY

Adipose-derived stem cell therapy offers plastic surgeons a novel treatment alternative for conditions with few therapeutic options. Adipose-derived stem cells are a promising treatment because of their broad differentiation potential, capacity for self-renewal, and ease of isolation. Over the past decade, plastic surgeons have attempted to harness adipose-derived stem cells' unique cellular characteristics to improve the survival of traditional fat grafting procedures, a process known as cell-assisted lipotransfer. However, the full implications of cell-assisted lipotransfer in clinical practice remain incompletely understood, stressing the urgent need to assess the scientific evidence supporting adipose-derived stem cell-based interventions. Furthermore, with the strict regulatory climate surrounding tissue explantation therapies, reviewing the safety and efficacy of these treatments will clarify their regulatory viability moving forward. In this report, the authors provide a comprehensive, up-to-date appraisal of best evidence-based practices supporting adipose-derived stem cell-derived therapies, highlighting the known mechanisms behind current clinical applications in tissue engineering and regenerative medicine specific to plastic and reconstructive surgery. The authors outline best practices for the harvest and isolation of adipose-derived stem cells and discuss why procedure standardization will elucidate the scientific bases for their broad use. Finally, the authors discuss challenges posed by U.S. Food and Drug Administration oversight of these cell-based therapies and examine the role of adipose-derived stem cell-based applications in the future of plastic surgery.

Effects of radiation and chemotherapy on adipose stem cells: Implications for use in fat grafting in cancer patients

Autologous fat transplantation is a versatile tool in reconstructive surgery. Adipose-derived stem cells (ASCs) increase survival of fat grafts and thus are increasingly used for breast reconstruction in breast cancer patients. However, radiation and/or chemotherapy have been proposed to inhibit soft tissue regeneration in wound healing thus suggesting alteration in stem cell pathways. Therefore, elucidating effects of radiation and chemotherapy on ASCs is critical if one desires to enhance the survival of fat grafts in patients. This review outlines our work evaluating the function and recoverability of ASCs from radiation or chemotherapy patients, focusing specifically on their availability as a source of autologous stem cells for fat grafting and breast reconstruction in cancer patients. Even though evidence suggests radiation and chemotherapy negatively influence ASCs at the cellular level, the efficiency of the isolation and differentiation capacity did not appear influenced in patients after receiving chemotherapy treatment, although fat from radiated patients exhibited significantly altered ASC differentiation into endothelial-like cells. Further, the in vitro growth rates of patient’s ASCs do not differ significantly before or after treatment. Taken together, these studies suggest ASCs as an important new tool for grafting and reconstruction even when radiation and chemotherapy treatment are involved.

Effect of Co-transplanting Stromal Vascular Fraction-Gelatin and Platelet-Rich Fibrin on the Long-Term Maintenance of Fat Volume

OBJECTIVE

In the present study, we aimed to investigate the survival of stromal vascular fraction-gelatin (SVF-gel) grafts and determine whether co-transplantation of SVF-gel and platelet-rich fibrin (PRF) improves long-term maintenance of fat volume (Wei et al. in Oncotarget 8:68542-68556, 2017) in a rabbit model.

METHODS

SVF-gel was transplanted into the ears of 12 rabbits with (experimental group) or without PRF (control group). Transplantation retention was evaluated based on weight, histology, and immunohistochemistry.

RESULTS

In the 2nd and 4th weeks, the volume of fat was larger in the experimental group than in the control group. In the 6th week, the absorption of fat was noticeable in both groups, and there was no significant difference in the fat survival rate between the two groups (experimental group: 1.051 ± 0.144 and control group: 0.789 ± 0.232, P > 0.05). HE staining results: At week 2, adipocytes were observed in the experimental group and tended to mature over time. These adipocytes also exhibited an ordered arrangement. Adipocytes with abnormal morphology appeared in the control group in the 4th week. At different weeks, there were more inflammatory cells and fibroblasts in the experimental group than in the control group, and they were arranged in an ordered fashion. Immunohistochemical results: More brown areas were observed in the experimental group than in the control group, and the morphology and distribution of adipocytes in the experimental group were better than those in the control group. The distribution of fibrocytes was also more regular in the experimental group than in the control group.

CONCLUSION

SVF-gel cannot maintain long-term filling in rabbit ears. The addition of PRF has no influence, although PRF can induce SVF-gel to transform into adipocytes, and the anti-inflammatory effect is noticeable in the early period following the procedure. Co-transplantation also helped to ensure orderly arrangement of fibrin. There were no "volume preservation differences in this experimental model" perhaps there are differences if other models/methodology are employed. No Level Assigned 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 Table of Contents or online Instructions to Authors - www.springer.com/00266 .

Effects of low-level laser therapy and adipose-derived stem cells on the viability of autologous fat grafts: a preliminary study

Background Autologous fat grafts are commonly used in cosmetic and reconstructive surgery, and various methods are used to improve their viability. Low-level laser therapy (LLLT) can enhance the proliferation, growth, and differentiation of various cell lines, including stem cells. Our study investigated and compared the effects of LLLT and the addition of adipose-derived stem cells (ADSCs) on the viability of fat grafts.Methods Twenty nude mice were divided into four groups: control (group 1), LLLT irradiation (group 2), ADSC addition (group 3), and LLLT irradiation+ADSC addition (group 4). ADSCs were combined with the fat tissue. LLLT irradiation was performed once daily for 1 week from the day of grafting. After 8 weeks, the weight, volume, histology, and Western blot findings of the grafted fat tissues were evaluated.Results The retention rate and volume of the fat tissue in groups 2, 3, and 4 were higher than that of group 1, but the difference was not statistically significant. The number of capillaries, histological parameters, and immunofluorescence staining analyses for CD68, CD31, fibroblast growth factor, and vascular endothelial growth factor (VEGF) showed no significant differences among the four groups. The expression level of VEGF was higher in group 2 than in the other groups, but not to a statistically significant level.Conclusions LLLT and ADSCs did not significantly improve the viability of autologous fat grafts. Therefore, further study is necessary to develop safe and effective methods to improve the viability of these grafts for clinical application.

Effects of macrophage regulation on fat grafting survival: Improvement, mechanisms, and potential application-A review

BACKGROUND

Autologous fat grafting has become a popular tool in plastic surgery to solve soft tissue defects and achieve skin rejuvenation, but the volume loss after transplantation remains a disturbing problem. In recent years, some new strategies have improved the outcome to some extent, but the fat graft retention is still far from ideal, so there remains a wide development prospect in this field. Macrophages are closely related to the local microenvironment and tissue regeneration, and their role in fat grafting has been increasingly highlighted.

AIMS

This article was aimed to review the efficacy, possible mechanisms, and potential application of macrophage regulation on fat grafting, as well as concerns and future perspectives of this filed.

METHODS

A retrospective review of the published data was conducted.

RESULTS

Most studies indicated that up-regulating M2 macrophages during fat grafting would improve fat retention via promoting neovascularization. M2 macrophages could secrete several pro-angiogenic factors, accelerate extracellular matrix (ECM) remodeling, and directly function on endothelial cells to encourage vascular expansion. In addition, macrophages could influence the proliferation, apoptosis, and adipogenic differentiation of preadipocytes.

CONCLUSIONS

During autologous fat grafting, appropriately regulating macrophages may become a promising method to increase fat retention. Nevertheless, the M2 macrophage polarizing agents, treatment opportunity, and contraindications require further discussion. We hope our work could promote more in-depth studies in this field, and we are looking forward to a standard procedure for the macrophage therapy in clinical practice.

'Fat chance': a review of adipose tissue engineering and its role in plastic and reconstructive surgery

Soft tissue reconstruction remains a continuing challenge for plastic and reconstructive surgeons. Standard methods of reconstruction such as local tissue transfer and free autologous tissue transfer are successful in addressing soft tissue cover, yet they do not come without the additional morbidity of donor sites. Autologous fat transfer has been used in reconstruction of soft tissue defects in different branches of plastic surgery, specifically breast and facial defect reconstruction, while further maintaining a role in body contouring procedures. Current autologous fat transfer techniques come with the drawbacks of donor-site morbidity and, more significantly, resorption of large amounts of fat. Advancement in tissue engineering has led to the use of engineered adipose tissue structures based on adipose-derived stem cells. This enables a mechanically similar reconstruct that is abundantly available. Cosmetic and mechanical similarity with native tissue is the main clinical goal for engineered adipose tissue. Development of novel techniques in the availability of natural tissue is an exciting prospect; however, it is important to investigate the potential of cell sources and culture strategies for clinical applications. We review these techniques and their applications in plastic surgery.

[Current review of factors in the stem cell donor that influence the regenerative potential of adipose tissue-derived stem cells]

BACKGROUND

Regenerative therapies like cell-assisted lipotransfer or preclinical experimental studies use adipose tissue-derived stem cells (ASCs) as the main therapeutic agent. But there are also factors depending on the clinical donor that influence the cell yield and regenerative potential of human ASCs and stromal vascular fraction (SVF). Therefore, the aim of this review was to identify and evaluate these factors according to current literature.

METHODS

For this purpose, a systematic literature review was performed with focus on factors affecting the regenerative potential of ASCs and SVF using the National Library of Medicine.

RESULTS

Currently, there is an abundance of studies regarding clinical donor factors influencing ASCs properties. But there is some contradiction and need for further investigation. Nevertheless, we identified several recurrent factors: age, sex, weight, diabetes, lipoedema, use of antidepressants, anti-hormonal therapy and chemotherapy.

CONCLUSION

We recommend characterisation of the ASC donor cohort in all publications, regardless of whether they are experimental studies or clinical trials. By these means, donor factors that influence experimental or clinical findings can be made transparent and results are more comparable. Moreover, this knowledge can be used for study design to form a homogenous donor cohort by precise clinical history and physical examination.

Human adipose-derived stem cells enriched with VEGF-modified mRNA promote angiogenesis and long-term graft survival in a fat graft transplantation model

Background

Fat grafting, as a standard treatment for numerous soft tissue defects, remains unpredictable and technique-dependent. Human adipose-derived stem cells (hADSCs) are promising candidates for cell-assisted therapy to improve graft survival. As free-living fat requires nutritional and respiratory sources to thrive, insufficient and unstable vascularization still impedes hADSC-assisted therapy. Recently, cytotherapy combined with modified mRNA (modRNA) encoding vascular endothelial growth factor (VEGF) has been applied for the treatment of ischemia-related diseases. Herein, we hypothesized that VEGF modRNA (modVEGF)-engineered hADSCs could robustly enhance fat survival in a fat graft transplantation model.

Methods

hADSCs were acquired from lipoaspiration and transfected with modRNAs. Transfection efficiency and expression kinetics of modRNAs in hADSCs were first evaluated in vitro. Next, we applied an in vivo Matrigel plug assay to assess the viability and angiogenic potential of modVEGF-engineered hADSCs at 1 week post-implantation. Finally, modVEGF-engineered hADSCs were co-transplanted with human fat in a murine model to analyze the survival rate, re-vascularization, proliferation, fibrosis, apoptosis, and necrosis of fat grafts over long-term follow-up.

Results

Transfections of modVEGF in hADSCs were highly tolerable as the modVEGF-engineered hADSCs facilitated burst-like protein production of VEGF in both our in vitro and in vivo models. modVEGF-engineered hADSCs induced increased levels of cellular proliferation and proangiogenesis when compared to untreated hADSCs in both ex vivo and in vivo assays. In a fat graft transplantation model, we provided evidence that modVEGF-engineered hADSCs promote the optimal potency to preserve adipocytes, especially in the long-term post-transplantation phase. Detailed histological analysis of fat grafts harvested at 15, 30, and 90 days following in vivo grafting suggested the release of VEGF protein from modVEGF-engineered hADSCs significantly improved neo-angiogenesis, vascular maturity, and cell proliferation. The modVEGF-engineered hADSCs also significantly mitigated the presence of fibrosis, apoptosis, and necrosis of grafts when compared to the control groups. Moreover, modVEGF-engineered hADSCs promoted graft survival and cell differentiation abilities, which also induced an increase in vessel formation and the number of surviving adipocytes after transplantation.

Conclusion

This current study demonstrates the employment of modVEGF-engineered hADSCs as an advanced alternative to the clinical treatment involving soft-tissue reconstruction and rejuvenation.

Which Fat Processing Can Achieve Optimal Transplantation in Patients With Insufficient Fat Resource?

BACKGROUND

Autologous fat transfer has been widely used in breast augment surgery. The breast fat graft is different form facial, it needs megavolume grafts. However, most Asian women are thin, who often encounter the fat resource insufficiency during breast augmentation. In fact, some processing methods do contribute to great loss of potential fat that could have been grafted. How to choose a best processing method to achieve optimal transfer in patients with insufficient fat resources is fairly important.

METHODS

Lipoaspirate was obtained from 10 healthy female patients who underwent liposuction from abdomen. According to the processing methods, 10-mL initial fat grafts divided into 4 groups: decantation (group A), centrifugation (group B), cotton pad (group C), and cell-assisted lipotransfer (CAL) (group D). Lipoaspirate from each group was compared in the vitro and vivo experiments. The content and function of stromal vascular fraction (SVF) were compared as well as lipoaspirate survival after grafting in nude mice.

RESULTS

The SVFs were counted in decantation group 4.32 ± 0.75 × 10/mL, centrifuge group 3.48 ± 0.78 × 10/mL, cotton pad group 1.64 ± 0.84 × 10/mL, CAL group 4.08 ± 0.73 × 10/mL. The decantation group was higher than the cotton pad group (P < 0.05). All the groups' SVFs had capability of multilineage differentiation. The fat graft weight in decantation group: 0.3908 ± 0.023 g, centrifuge group 0.3073 ± 0.015 g, cotton pad group 0.1726 ± 0.019 g, and CAL group 0.2396 ± 0.021 g. The weight of the fat graft in the decantation group was greater than that of the centrifugation group, cotton pad group and CAL group (P < 0.05). There was no significant difference in cell integrity, necrotic cysts and fibrosis between the groups. The vascularization degree in the cotton pad group was lower than that in the decantation group (P < 0.05).

CONCLUSIONS

Decantation processing can achieve optimal transplantation in patients who have insufficient fat resources.

Adipose-derived stem cell enrichment is counter-productive for the majority of women seeking primary aesthetic breast augmentation by autologous fat transfer: A systematic review

BACKGROUND

Autologous lipotransfer (AL) is a popular method despite unpredictable retention rates. Higher retention rates have been reported when co-administering adipose-derived stem cells (ASCs), a process called cell-assisted lipotransfer (CAL). Our hypothesis is that CAL might indeed limit volume gain in most women seeking aesthetic breast augmentation because it doubles the amount of fat required without consistently improving the outcome.

METHODS

Electronic databases were searched for articles published between January 2008 and October 2019 in English and German. All original articles evaluating fat viability following autologous breast augmentation in vivo were included. Based on the reported retention rates, potential volume gains were estimated for CAL and AL.

RESULTS

A total of 23 studies were selected. The AL retention rate varied from 39% to 76%, whereas CAL increased this rate at best by 24%. The body mass index (BMI) ranged from 18.8 to 23.4 (20.4±1.6) in the study population, whereas the BMI of women in the same age group is 28.7 (±8.4). We calculated that, starting from 200 ml of harvested fat and after two sessions of AL of 100 ml each, the volume retained would be at most 152 ml. In contrast, after one session of CAL of 100 ml, while the remaining 100 ml are used to isolate ASCs, a maximum of 95 ml of fat would remain.

CONCLUSION

The volume gain after two sessions of AL is far superior to that after one session of CAL for the same volume of harvested fat. This is an important practical consideration for women with low BMI, as the extra fat required to isolate ASCs is not counterbalanced by an increase in the retention rate. Therefore, two sessions of AL may be preferable to maximize the volume gain.

Isolation and identification of adipose-derived stromal/stem cells from breast cancer patients after exposure neoadjuvant chemotherapy

BACKGROUND

With recent research advances, adipose-derived stromal/stem cells (ASCs) have been demonstrated to facilitate the survival of fat grafts and thus are increasingly used for reconstructive procedures following surgery for breast cancer. Unfortunately, in patients, following radiation and chemotherapy for breast cancer suggest that these cancer treatment therapies may limit stem cell cellular functions important for soft tissue wound healing. For clinical translation to patients that have undergone cancer treatment, it is necessary to understand the effects of these therapies on the ASC's ability to improve fat graft survival in clinical practice.

AIM

To investigate whether the impact on ASCs function capacity and recovery in cancer patients may be due to the chemotherapy.

METHODS

ASCs were isolated from the cancerous side and noncancerous side of the breast from the same patients with receiving neoadjuvant chemotherapy (NAC) or not-receiving NAC. ASCs were in vitro treated with 5-fluorouracil (5-FU), doxorubicin (DXR), and cyclophosphamide (Cytoxan) at various concentrations. The stem cells yield, cell viability, and proliferation rates were measured by growth curves and MTT assays. Differentiation capacity for adipogenesis was determined by qPCR analysis of the specific gene markers and histological staining.

RESULTS

No significant differences were observed between the yield of ASCs in patients receiving NAC treatment and not-receiving NAC. ASCs yield from the cancerous side of the breast showed lower than the noncancerous side of the breast in both patients receiving NAC and not-receiving NAC. The proliferation rates of ASCs from patients didn't differ much before and after NAC upon in vitro culture, and these cells appeared to retain the capacity to acquire adipocyte traits simile to the ASCs from patients not-receiving NAC. After cessation and washout of the drugs for another a week of culturing, ASCs showed a slow recovery of cell growth capacity in 5-FU-treated groups but was not observed in ASCs treated with DXR groups.

CONCLUSION

Neoadjuvant therapies do not affect the functioning capacity of ASCs. ASCs may hold great potential to serve as a cell source for fat grafting and reconstruction in patients undergoing chemotherapy.

MEG3 regulates apoptosis of adipose‑derived stem cells

In plastic surgery, the maneuverability and safety of autologous fat transplantation have become increasingly recognized and continuously improved. However, the uncertainty of adipocyte survival makes it difficult to predict postoperative effects. Adipose‑derived stem cells (ADSCs) exhibit remarkable paracrine activity, and the number of ADSCs in adipose tissue is closely related to tissue survival. Maternally expressed gene 3 (MEG3) is known to modulate the apoptosis of various cell types. The present study aimed to evaluate the hypothesis that MEG3 serves an important role in ADSC apoptosis by regulating the expression of p53, and to explore the regulatory mechanisms of p53 in ADSC apoptosis. MEG3 was overexpressed in ADSCs and these cells were evaluated for viability, TP53 expression, apoptosis, morphology, and Bax and Bcl‑2 expression by performing MTT assays, reverse transcription‑quantitative PCR, flow cytometry analysis and western blotting. This study demonstrated that MEG3 may have an important role in the spontaneous apoptosis of ADSCs, and apoptosis induced by oxidative stress. In addition, this study revealed that p53 had a regulatory role in the downstream Bcl‑2/Bax pathway. This study provides insight into the role of MEG3 in ADSC apoptosis, thereby facilitating the survival of ADSCs during adipose tissue transplantation. Further in vivo and in vitro experiments should be conducted, along with the development of clinical applications.

Introduction of ligated vessels promote the retention and regeneration of free fat: constructing a fat flap in tissue engineering chamber

Background: Breast reconstruction with fat grafting has an unstable retention rate due to insufficient revascularization. Tissue Engineering Chamber (TEC) model can promote tissue regeneration in the chamber by introducing ligated vessels around the tissue. We introduced ligated vessels with free fat graft to investigate the retention rate and revascularization of grafted fat that in TEC model.

Methods: SD rats (n=24) was divided into 3 groups randomly. Group A: Standard TEC model was constructed; Group B: the epigastric vessel bundles were dissected from the fat flap and ligated, fat flap was cut into granules and planted into the chamber; Group C: Free fat was planted in the chamber. At week 6, samples in the chamber were harvested.

Results: Significant volume increase was observed in group A and B, while the volume decreased in group C (P<0.05). Regeneration morphology could be found according to the histological observation in A and B. Micro CT results showed the ligated vessels into grafted fat sprouting robustly, coordinated with volume changes.

Conclusion: Fat grafts in TEC model could not only survive but also regenerate. The combination of fat graft and TEC could fabricate a vascularized fat flap, which was a promising method in breast reconstruction.

Abbreviations: VOI: Volumes of Interest; TEC: Tissue Engineering Chamber; CAL: Cell Assisted Lipotransfer.

Exosomes Are Comparable to Source Adipose Stem Cells in Fat Graft Retention with Up-Regulating Early Inflammation and Angiogenesis

BACKGROUND

Exosomes derived from mesenchymal stem cells possess functional properties similar to those of their parent cells, suggesting that they could play a pivotal role in tissue repair and regeneration.

METHODS

Using lipotransfer as a surrogate, exosomes were isolated from mouse adipose-derived stem cell-conditioned medium and characterized. Minced fat tissue mixed with exosomes, source cells (cell-assisted lipotransfer), or saline was implanted subcutaneously in the lower back of C57/BL mice bilaterally (n = 16 each). Transferred fat tissues were harvested and analyzed at 3 and 10 weeks.

RESULTS

At 3 and 10 weeks after the transfer, fat grafts in groups of exosomes and cell-assisted lipotransfer showed better fat integrity, fewer oil cysts, and reduced fibrosis. At week 10, graft retention rates in cell-assisted lipotransfer (50.9 ± 2.4 percent; p = 0.03) and exosome groups (56.4 ± 1.6 percent; p < 0.001) were significantly higher than in the saline group (40.7 ± 4.7 percent). Further investigations of macrophage infiltration, inflammatory factors, angiogenic factors, adipogenic factors, and extracellular matrix revealed that those exosomes promoted angiogenesis and up-regulated early inflammation, whereas during mid to late stages of fat grafting, they exerted a proadipogenic effect and also increased collagen synthesis level similarly to their source cells.

CONCLUSIONS

The adipose-derived stem cell-derived exosomes demonstrated effects comparable to those of their source cells in achieving improved graft retention by up-regulating early inflammation and augmenting angiogenesis. These features may enable exosomes to be an attractive cell-free alternative in therapeutic regenerative medicine.

Cell-Enriched Fat Grafting Improves Graft Retention in a Porcine Model: A Dose-Response Study of Adipose-Derived Stem Cells versus Stromal Vascular Fraction

BACKGROUND

Cell-enrichment of fat grafts has produced encouraging results, but the optimal concentrations and types of added cells are unknown. The authors investigated the effects of enrichment with various concentrations of ex vivo-expanded adipose-derived stem/stromal cells and stromal vascular fraction on graft retention in a porcine model.

METHODS

Adipose-derived stem/stromal cells were culture-expanded, and six fat grafts (30 ml) were prepared for each minipig (n = 13). The authors investigated grafts enriched with 2.5 × 10 to 20 × 10 adipose-derived stem cells/ml and stromal vascular fraction and nonenriched control grafts. Each pig served as its own control. Magnetic resonance imaging was performed immediately after grafting and 120 days postoperatively before the pigs were euthanized, and histologic samples were collected.

RESULTS

The authors recorded an enhanced relative graft retention rate of 41 percent in a pool of all cell-enriched grafts compared to the nonenriched control (13.0 percent versus 9.2 percent; p = 0.0045). A comparison of all individual groups showed significantly higher graft retention in the 10 × 10-adipose-derived stem/stromal cells per milliliter group compared with the control group (p = 0.022). No significant differences were observed between the cell-enriched groups (p = 0.66). All fat grafts showed a significantly better resemblance to normal fat tissue in the periphery than in the center (p < 0.009), but no differences in overall graft morphology were observed between groups (p > 0.17).

CONCLUSIONS

Cell-enriched fat grafting improved graft retention and was feasible in this porcine model. No significant differences in graft retention were observed among the various adipose-derived stem/stromal cell concentrations or between adipose-derived stem/stromal cell and stromal vascular fraction enrichment. Future studies using this model can help improve understanding of the role of adipose-derived stem/stromal cells in cell-enriched fat grafting.

Preenrichment with Adipose Tissue-Derived Stem Cells Improves Fat Graft Retention in Patients with Contour Deformities of the Face

Quick absorption of adipose tissue grafts makes the outcomes less satisfactory for clinical applications. In the current study, adipose tissue grafts were mixed with adipose tissue-derived stem cells (ASCs) to improve retention of adipose tissue grafts and to make the clinical outcomes of fat grafting more reliable. Adipose tissue was either injected alone (conventional group) or mixed with ASCs (stem cell group) before injection. In both groups, adipose tissue was injected at the site of contour throughout layers of tissues till visual clinical symmetry with the opposite side was achieved. The volume of injected fat graft was measured after 72 hours and 6 months using a B-mode ultrasound device connected with a 12 MH frequency probe. The percentage reduction in the volume of injected fat, physician satisfaction scores (Ph-SCs), and patient satisfaction scores (P-SCs) were also recorded. After 6 months, there was significantly lower fat absorption in the stem cell group as compared to the conventional group. Mean physician and patient satisfaction scores were significantly improved in the stem cell group. No significant adverse effects were noted in any patient. Significantly lower absorption of graft due to the use of ASCs improves the clinical outcomes of conventional fat grafting for contour deformities of the face. The current preenrichment strategy is noninvasive, safe and can be applied to other diseases that require major tissue augmentation such as breast surgery. This trial is registered with NCT02494752.

The Effect of Early Rounds of ex vivo Expansion and Cryopreservation on the Adipogenic Differentiation Capacity of Adipose-Derived Stromal/Stem Cells

Multipotent adipose-derived stromal/stem cells (ASCs) are candidates for use in cellular therapies for the treatment of a variety of conditions/diseases. Ex vivo expansion of freshly isolated ASCs may be necessary prior to clinical application to ensure that clinically relevant cell numbers are administered during treatment. In addition, cryopreserving cells at early passages allows for storage of freshly isolated cells for extended periods of time before expanding these cells for clinical usage. There are however several concerns that these laboratory-based procedures may alter the characteristics of the cells and in so doing decrease their regenerative potential. In this study we report on the impact of early rounds of cryopreservation (P0) and ex vivo expansion (P0 to P5) on the phenotypic characteristics and adipogenic differentiation potential of ASCs. Our results show that ASCs that upregulate CD36 expression during adipogenic differentiation gradually decrease with increasing expansion rounds. The consequent decrease in adipogenic differentiation capacity was evident in both gene expression and flow cytometry-based phenotypic studies. Successive rounds of expansion did not however alter cell surface marker expression of the cells. We also show that early cryopreservation of ASCs (at P0) does not affect the adipogenic differentiation potential of the cells.

Office-Based Autologous Fat Injection Laryngoplasty for Glottic Insufficiency in Patients Under 50 Years Old

OBJECTIVE

We sought to determine the outcomes of office-based autologous fat injection laryngoplasty in the treatment of patients under 50 years old with glottic insufficiency but without neurological problems or acquired organic lesions in the vocal fold.

METHODS

We conducted a retrospective chart review of consecutive patients under 50 years of age who underwent office-based autologous fat injection laryngoplasty for glottic insufficiency. None of the patients presented neurological problems or acquired organic lesions in the vocal fold. Videolaryngostroboscopic data, objective voice assessment, perceptual measurements of vocal quality, and subjective ratings of voice quality were evaluated before and after treatment.

RESULTS

The 23 patients (7 men and 16 women) in this study presented significant improvements in phonatory function in terms of maximum phonation time, jitter, grade, asthenia, and Voice Handicap Index-10 (VHI-10) values at 3 months. Significant improvements in terms of jitter, noise-to-harmonic ratio, grade, roughness, breathiness, asthenia, and the VHI-10 values were also observed at 6 months.

CONCLUSIONS

Glottic insufficiency in younger patients without neurological problems or acquired organic lesions in the vocal fold can be treated effectively using office-based autologous fat injection laryngoplasty. Significant improvements in phonatory function were observed even 6 months after surgery.

The Future of Facial Fat Grafting

Fat grafting was first described in the early 20th century but for many years remained a relatively underused technique due to the unreliability of long-term volume expansion. Significant improvements in reliability have been made in the last 2 decades and there is a large body of literature pertaining to extraction, processing and injection methods to obtain more lasting effects. However, volume loss and graft resorption remain a major challenge in the long term and lead to unpredictability in results. Enriching adipose graft with stromal vascular fraction, ex vivo cultured adipose stem cells and platelet-derived growth factor among others is one method under active investigation which may assist graft survival through a range of mechanisms including increased angiogenesis. Breaking adipose graft into smaller fragments such that engrafted cells have greater access to donor-site oxygenation and nutrition is another method which in theory may promote survival. Presently, adipose grafting in the face is usually for the addition of volume to fill defects. However, the stem-cell containing fraction of adipose grafting (stromal vascular fraction) appears to exert a rejuvenating effect on overlying skin and soft tissue when administered alone. The application of these low-volume injections represents a significant shift in thinking away from mere volume expansion. These techniques have been tested in a range of animal models and some human studies. In this review, the authors provide a broad overview of present research and highlight both limitations in previous research and current areas of investigation.

Endothelial Differentiated Adipose-Derived Stem Cells Improvement of Survival and Neovascularization in Fat Transplantation

Background

Adipose-derived stem cells (ASCs) assisted lipotransfer have been considered to facilitate the survival of fat grafts. However, emerging evidence of insufficient vascularization is another obstacle for fat graft survival in cell-assisted lipotransfer.

Objectives

This study evaluated if endothelial phenotype ASCs with fat lipoaspirate improves survival and neovascularization in fat transplantation.

Methods

ASCs were isolated from human periumbilical fat tissue and cultured in endothelial growth medium for 2 weeks. Fat lipoaspirate was mixed with fresh adipose stroma vascular fraction (SVF), endothelial differentiated ASCs (EC/ASCs), and fat lipoaspirate alone. Three fat mixtures were subcutaneously injected into the adult male Sprague-Dawley rat's dorsum at 3 locations. At 8 weeks after transplantation, the grafted fat lipoaspirates were harvested, and the extracted fat was evaluated using photographic, survival weights measurements and histological examination. Neo-vascularization was quantified by immunofluorescence and real-time RT-PCR.

Results

Grafts from the EC/ASC assisted group had a higher survival rate, morphologic integrity, and most uniform lipid droplets. They also revealed less inflammation and fibrosis with increased number of vessels by histological and immunofluorescence analysis. Quantitative RT-PCR analysis indicated that the expression levels of EC-specific markers of CD31 and vWF were higher in the EC/ASC group compared with in the control and fat with SVF transplants.

Conclusions

These results indicated that co-implantation of fat lipoaspirate with ASCs differentiated toward an endothelial phenotype improves both survival and neovascularization of the transplanted fat lipoaspirate, which might provide benefits and represents a promising strategy for clinical application in autologous fat transplantation.

Generation of Functional Human Adipose Tissue in Mice from Primed Progenitor Cells

Adipose tissue (AT) is used extensively in reconstructive and regenerative therapies, but transplanted fat often undergoes cell death, leading to inflammation, calcification, and requirement for further revision surgery. Previously, we have found that mesenchymal progenitor cells within human AT can proliferate in three-dimensional culture under proangiogenic conditions. These cells (primed ADipose progenitor cells, PADS) robustly differentiate into adipocytes in vitro (ad-PADS). The goal of this study is to determine whether ad-PADS can form structured AT in vivo, with potential for use in surgical applications. Grafts formed from ad-PADS were compared to grafts formed from AT obtained by liposuction after implantation into nude mice. Graft volume was measured by microcomputed tomography scanning, and the functionality of cells within the graft was assessed by quantifying circulating human adiponectin. The degree of graft vascularization by donor or host vessels and the content of human or mouse adipocytes within the graft were measured using species-specific endothelial and adipocyte-specific quantitative real time polymerase chain reaction probes, and histochemistry with mouse and human-specific lectins. Our results show that ad-PADS grafted subcutaneously into nude mice induce robust vascularization from the host, continue to increase in volume over time, express the human adipocyte marker PLIN1 at levels comparable to human AT, and secrete increasing amounts of human adiponectin into the mouse circulation. In contrast, grafts composed of AT fragments obtained by liposuction become less vascularized, develop regions of calcification and decreased content of PLIN1, and secrete lower amounts of adiponectin per unit volume. Enrichment of liposuction tissue with ad-PADS improves vascularization, indicating that ad-PADS may be proangiogenic. Mechanistically, ad-PADS express an extracellular matrix gene signature that includes elements previously associated with small vessel development (COL4A1). Thus, through the formation of a proangiogenic environment, ad-PADS can form functional AT with capacity for long-term survival, and can potentially be used to improve outcomes in reconstructive and regenerative medicine.

Does Stromal Vascular Fraction Ensure a Higher Survival in Autologous Fat Grafting for Breast Augmentation? A Volumetric Study Using 3-Dimensional Laser Scanning

Background

Cell-assisted lipotransfer (CAL) has been considered a promising technique for promoting adipogenesis and angiogenesis in fat grafts.

Objectives

The author sought to objectively analyze the change of breast volume in patients who underwent stromal vascular fraction (SVF)-enriched fat grafting for breast augmentation and compared the clinical results with those who underwent conventional fat grafting without SVF by using 3-dimensional laser scanning.

Methods

From April 2015 to March 2016, 105 patients who underwent traditional fat grafting without SVF enrichment for breast augmentation were assigned to group A and served as the control. The other 101 patients who underwent SVF-enriched fat grafting for breast augmentation were assigned to group B. The charts of these patients were retrospectively reviewed.

Results

The survival rate of the transplanted fat was 67.9% in group A and 68.7% in group B at 12 months after the operation. Postoperative complication rate was 3.8% in group A and 5.9% in group B. The differences were statistically insignificant.

Conclusions

SVF does not ensure a higher survival rate in autologous fat grafting for breast augmentation. Considering the potential drawbacks of adipose-derived stem cells (ADSC) and the extra cost of the consumables, in particular the need for harvesting larger amount of fat which could be reserved for additional fat grafting at a later time to achieve even better improvement, the results of this study do not support the use of SVF in autologous fat grafting for breast augmentation in terms of graft survival and postoperative complications.

Level of Evidence 3

The CD34+ Cell Number Alone Predicts Retention of the Human Fat-Graft Volume in a Nude Mouse Model

Prediction of the final transferred fat volume is essential for the success of fat grafting, but remains elusive. Between 20 and 80 % of the initial transplanted volume can be reabsorbed. Although graft survival has many determinants, CD34+ progenitor cells from the vascular stroma of adipose tissue play a central role by promoting growth of blood vessels and adipocytes. We aimed to verify the hypothesis that a higher proportion of total CD34+ cells in the transplant is associated with better preservation of the graft volume. Human lipoaspirates from 16 patients were processed by centrifugation and two grafts per donor were subcutaneously injected into 32 nude mice in 1 ml volumes in the right upper flank area. The volume of each graft was measured using a preclinical MRI scanner immediately after grafting and at three months. The percentage of CD34+ cells in the graft before implantation was determined by flow cytometry. The final graft volume at three months after implantation directly correlated with the percentage of CD34+ cells in the grafted material (r = 0.637, P = 0.019). The minimum retention of the fat graft was 28 % and the maximum retention was 81 %, with an average of 54 %. Our study found that fat retention after fat transfer directly correlated with the fraction of CD34+ cells in the graft. The simple and fast determination of the CD34+ cell percentage on site can help predicting outcomes of fat transplantation.

Adipose Stromal Vascular Fraction Gel Grafting: A New Method for Tissue Volumization and Rejuvenation

BACKGROUND

The clinical outcomes of fat grafting vary and are technique-dependent. Stromal vascular fraction (SVF) gel is a novel, mechanically processed fat product with high concentrations of adipose tissue-derived stem cells and other SVF cells. This study evaluated the volumization and rejuvenation effects of SVF-gel.

OBJECTIVE

This study evaluated the volumization and rejuvenation effects of SVF-gel.

METHODS

This retrospective, single-center study included 126 patients who underwent SVF-gel grafting and 78 who underwent conventional lipoinjection for various indications from March 2015 to February 2017. Patient satisfaction and secondary surgery rates were evaluated. Samples of transferred SVF-gel were harvested and examined histologically.

RESULTS

All patients showed improvements in facial augmentation and contour. Patients in the SVF-gel group experienced mild postoperative swelling and a low secondary surgery rate (10.9%). Assessment of patient-rated satisfaction on a 5-point Likert scale found that 77.3% of patients in the SVF-gel group were satisfied (54.5%) or very satisfied (22.8%) with their outcomes. By comparison, 53.8% of patients who underwent conventional lipoinjection were satisfied (48.7%) or very satisfied (5.1%). Moreover, SVF-gel showed effective antiwrinkle and skin rejuvenation effects. Hematoxylin-eosin staining showed a normal adipose tissue structure in transferred SVF-gel.

CONCLUSION

Stromal vascular fraction gel is effective for both volumization and rejuvenation, and may be superior to conventional lipoinjection for facial recontouring.

Effects of VEGF-ANG-1-PLA nano-sustained release microspheres on proliferation and differentiation of ADSCs

The improvement of fat graft viability might depend on the presence of multipotent resident adipose derived stem cells (ADSCs) which is the important component of stromal vascular fraction (SVF). Vascular endothelial growth factor (VEGF) and angiogenin-1 (Ang-1) are responsible for neovascularization. However, their half-life is too short to produce a biological effect. We thus investigated whether VEGF-ANG-1-polylactic acid (PLA) microspheres could enhance the angiogenic properties of ADSCs. PLA microspheres containing VEGF and ANG-1 were prepared by in vitro ultrasonic emulsification and characterized according to their encapsulation efficiency (EE), drug-loading rate (DL), particle size, and drug release. The systemic toxicity of empty loaded nanospheres (NPs) and the ability of these microspheres to promote the proliferation and differentiation of ADSCs were evaluated. The EE and DL were above 86% and 0.0288%, respectively [corrected].The drug release was completed after 20 days. Systemic toxicity was verified in ADSCs that received the unloaded NPs. It was observed that ADSCs treated with VEGF-ANG-1-PLA microspheres had an increase in the proliferation and the number of CD31 positive cells. ADSCs proliferation and differentiation toward endothelial cells (ECs) could be enhanced by the addition of VEGF-ANG-1-PLA nano-sustained release microspheres.