The Role of Recipient Sites in Fat-Graft Survival

The Optimal Layer for Breast Augmentation in an Autologous Fat Grafting Murine Model

BACKGROUND

Fat grafting is an effective procedure for breast augmentation, but the variations in this technique result in unpredictable fat retention. Therefore, animal models are needed to simulate the operation and the optimal layer for fat retention.

OBJECTIVES

An autologous fat grafting murine model for breast augmentation was built to detect a new layer for fat grafting in the chest.

METHODS

The left side of the female rat inguinal fat flap was harvested, dissected into small pieces, and autotransplanted into 3 different layers of the breast. Retention rate and hematoxylin and eosin (H&E) staining were measured at 1, 4, 8 12, and 16 weeks. Immunofluorescence staining was utilized to detect adipocytes and endothelial cells, and immunohistochemistry was conducted to evaluate the expression of integrins β1 and α6.

RESULTS

The volume of fat grafts slightly grew in the intramuscular and submuscular layers at Week 4. Retention rates in the subcutaneous layer and submuscular layer were significantly higher than the intramuscular layer at Week 16. H&E staining showed that oil cysts existed in the subcutaneous layer throughout the 16 weeks. At the terminal time point, well-vascularized mature adipose structures were observed in intramuscular and submuscular layers, with smaller adipocytes in intramuscular layers. Immunohistochemistry analysis showed that integrin β1 was identically expressed in every adipocyte in all the layers, whereas integrin α6 selectively expressed in bigger adipocytes in the intramuscular layer. The expression intensities of integrin β1 and α6 were significantly higher in the intramuscular layer than in the subcutaneous and submuscular layers.

CONCLUSIONS

The angiogenic and moderate mechanical environment makes the submuscular layer the optimal layer for fat retention.

The effect of host tissue and radiation on fat-graft survival: A comparative experimental study

Because lipofilling is often associated with various reconstructive procedures, especially breast reconstructions, improving fat-graft retention remains a major concern for plastic surgeons. We conducted an experimental protocol in a rat model simulating an autologous breast reconstruction method using the fat-augmented latissimus dorsi myocutaneous (LDM) flap. This study aimed to compare the survival rates of autologous adipocytes when injected subcutaneously and intramuscularly and to evaluate the role of recipient host tissue, volume of the injected fat, and postoperative radiation on fat-graft retention. Thirty rats were divided into five groups (A, B, C, D, and E), of six rats each. All animals underwent a pedicled LDM flap transfer to the anterior thoracic wall, and different volumes of autologous fat were injected into three recipient areas, namely, the pectoralis major and latissimus dorsi muscles and the subcutaneous tissue of the flap's skin island, as follows: 1 mL of fat was injected in total in group A, 2 mL in groups B and D, and 5 mL in group C. Group D animals received postoperative radiation (24 Gy), whereas group E animals (controls) did not undergo any fat grafting procedure. Eight weeks after surgery, adipocyte survival was assessed in all groups using histological and immunochemistry techniques. The results showed that the pectoralis major muscle was the substrate with the highest adipocyte survival rates, which were proportional to the amount of fat injected, followed by the latissimus dorsi muscle and the subcutaneous tissue. Increased volumes of transplanted fat into the subcutaneous tissue did not correspond to increased adipocyte survival. Irradiation of host tissues resulted in a statistically significant decrease in surviving adipocytes in all three recipient sites (p<0.001). Our study strongly suggests that muscle ensures optimal fat-graft retention, whereas postoperative radiation negatively affects adipocyte survival following fat transplantation.

Progress and obstacles in transplantation of brown adipose tissue or engineered cells with thermogenic potential for metabolic benefits

Transplantation of brown adipose tissue (BAT), engineered thermogenic progenitor cells, and adipocytes have received much attention for the improvement of obesity and metabolic disorders. However, even though the thermogenic and metabolic potential exists early after transplantation, the whitening of the brown fat graft occurs with metabolic function significantly impaired. In this review, specific experiment designs, graft outcomes, and metabolic benefits for the transplantation of BAT or engineered cells will be discussed. The current advancements will offer guidance to further investigation, and the obstacles appearing in previous studies will require innovation of BAT transplantation methods.

Optimizing Prepectoral Implant Placement and Concomitant Fat Grafting After Tissue Expansion

BACKGROUND

Prepectoral implant-based breast reconstruction is often supplemented by autologous fat grafting to optimize aesthetic outcomes. This usually entails several rounds of modest fat transfer to minimize risk of necrosis; however, the limits of fat grafting at expander exchange are not known.

METHODS

A single-institution retrospective review from July 2016 to February 2022 was performed of all patients who underwent (1) mastectomy, (2) prepectoral tissue expander placement, (3) expander exchange for implant, and (4) at least one round of autologous fat transfer. Student t test and χ2 test were used.

RESULTS

A total of 82 breasts underwent a single round of fat grafting during implant placement (group 1); 75 breasts underwent fat grafting that occurred in multiple rounds and/or in delay to implant placement (group 2). Group 1 received more fat at the time of implant placement (100 mL; interquartile range, 55-140 mL; P < 0.001) and underwent fewer planned operative procedures compared with group 2 (1.0 vs 2.2, P < 0.001). Total fat volume in group 2 did not significantly exceed that of group 1 until after 3 rounds of fat transfer (128.5 mL; interquartile range, 90-130 mL; P < 0.01). There was no difference in the rate of fat necrosis between groups after the first round (15.9% vs 9.3%, P = 0.2) and final round (15.9% vs 12.0%, P = 0.5) of fat grafting. Complication rates were similar between groups (3.7% vs 8.0%, P = 0.2).

CONCLUSIONS

A 2-stage approach of prepectoral tissue expander placement with single round of larger volume fat transfer at expander exchange reduces overall number of operative procedures without increased risks.

Fat grafting and platelet-rich plasma in wound healing: a review of histology from animal studies

Stem cells could form the basis of a novel, autologous treatment for chronic wounds like diabetic foot ulcers. Fat grafts contain adipose-derived stem cells (ADSC) but low survival of cells within the grafts is a major limitation. Platelet-rich plasma (PRP) may increase graft survival. This review examines the histology from animal studies on fat grafting, ADSC and PRP in wound healing. A literature review of major electronic databases was undertaken, and narrative synthesis performed. Data from 30 animal studies were included. ADSC increase angiogenesis over 14 days and often clinically accelerated wound healing. ADSC had a greater effect in animals with impaired wound healing (e.g. diabetes). Activated PRP increased viability of fat grafts. Despite the high number of studies, the quality is variable which weakens the evidence. It does suggest there is a benefit of ADSC, particularly in impaired wound healing. High-quality evidence in humans is required, to establish its clinical usefulness.

Quality and Quantity-Cultured Human Mononuclear Cells Improve Human Fat Graft Vascularization and Survival in an In Vivo Murine Experimental Model

BACKGROUND

Fat graft ischemia impedes us from having satisfying long-term results. The quality and quantity culture is a 1-week cell culture that increases the vasculogenic potential of peripheral blood mononuclear cells (PBMNC). This in vivo murine model investigates whether enrichment with quality and quantity-cultured human mononuclear cells (MNC-QQ) improves the vascularization in the human fat graft and whether this decreases the tissue loss.

METHODS

Human adipose tissue, PBMNC, MNC-QQ, and stromal vascular fraction were prepared. First, PBMNC, MNC-QQ, and stromal vascular fraction were compared in vitro for vasculogenic potential by endothelial progenitor cell colony-forming and culture assays. Second, 0.25-g fat grafts were created with 1 × 106 PBMNC (n = 16), 1 × 106 MNC-QQ (n = 16), 1 × 106 stromal vascular fraction (n = 16), or phosphate-buffered saline as control (n = 16) before grafting in BALB/c nude mice. Grafts were analyzed for weight persistence, vessel formation by CD31 immunohistochemistry, and angiogenic markers by quantitative polymerase chain reaction.

RESULTS

MNC-QQ develop more definitive endothelial progenitor cell colonies and more functional endothelial progenitor cells compared to PBMNC and stromal vascular fraction. Weight persistence after 7 weeks was significantly higher in grafts with MNC-QQ (89.8 ± 3.5 percent) or stromal vascular fraction (90.1 ± 4.2 percent) compared with control (70.4 ± 6.3 percent; p < 0.05). MNC-QQ-enriched grafts had the highest vessel density (96.6 ± 6.5 vessels/mm2; control, 70.4 ± 5.6 vessels/mm2; p < 0.05). MNC-QQ exerted a direct vasculogenic effect through vascular integration and a potential paracrine vascular endothelial growth factor-mediated effect.

CONCLUSION

Quality and quantity-cultured human mononuclear cells containing endothelial progenitor cells stimulate fat graft vascularization and enhance graft survival in a rodent recipient.

Photobiomodulation with polychromatic light (600-1200 nm) improves fat graft survival by increasing adipocyte viability, neovascularization, and reducing inflammation in a rat model

OBJECTIVES

Unpredictability with the final volume and viability of the graft are the major concerns in fat grafting. An experimental study was conducted to increase graft retention using photobiomodulation (PBM) with polychromatic light in near-infrared region (600-1200 nm) by utilizing its stimulatory effects on angiogenesis, neovascularization, adipocyte viability, and anti-inflammatory properties.

METHODS

A total of 24 rats were divided into four groups (n = 6) according to the applied polychromatic light protocol to the recipient site (none, before fat transfer, after fat transfer, and combined). In all groups, inguinal fat pad was excised, measured for volume and weight, and transferred to the dorsum of the rat. At the end of the experiment, fat grafts were harvested from the recipient site for volume and weight measurements, histological, and immunohistochemical evaluation.

RESULTS

Intergroup comparison revealed that fat graft retention regarding weight and volume, was significantly superior in Group IV (p = 0.049 and p = 0.043, respectively), which polychromatic light was applied both before and after transfer of the graft. Hematoxylin-eosin and Masson's trichrome stained sections showed absence of necrosis, fibrosis, inflammation, cyst formation, and increased vascularization of both inner and outer zones of the grafts in Group IV. Also, immunohistochemical staining scores for perilipin (indicator for adipocyte viability), CD31 and VEGF (indicators for angiogenesis and neovascularization) were significantly higher (p < 0.001). Ki67 scores were significantly lower in this group because of anti-inflammatory environment (p < 0.001).

CONCLUSIONS

Application of PBM to the recipient site before and after fat transfer improved outcomes in rats at 56 day after fat grafting by means of volume retention, increased neovascularization and adipocyte viability and reduced necrosis, fibrosis and inflammation.

Surgical Decision Making in Autologous Fat Grafting: An Evidence-Based Review of Techniques to Maximize Fat Survival

Autologous fat grafting is an important tool in plastic surgery and is widely used for a variety of applications, both aesthetic and reconstructive. Despite an ever-increasing list of indications and extensive research over many years into improving outcomes, fat grafting remains plagued by incomplete and often unpredictable graft survival. Decisions made at each stage of surgery can potentially contribute to ultimate success, including donor site selection and preparation, fat harvest, processing, and purification of lipoaspirate, recipient site preparation, and delivery of harvested fat to the recipient site. In this review, we examine the evidence for and against proposed techniques at each stage of fat grafting. Areas of consensus identified include use of larger harvesting and grafting cannulas and slow injection speeds to limit cell damage due to shearing forces, grafting techniques emphasizing dispersion of fat throughout the tissue with avoidance of graft pooling, and minimizing exposure of the lipoaspirate to the environment during processing. Safety considerations include use of blunt-tipped needles or cannulas to avoid inadvertent intravascular injection as well as awareness of cannula position and avoidance of danger zones such as the subgluteal venous plexus. We believe that using the evidence to guide surgical decision-making is the key to maximizing fat grafting success. Level of Evidence: 4.

Impact of Fat Graft Thickness and Harvesting Technique on Adipocyte Viability in a New Porcine Experimental Model: An Immunohistochemical Analysis

BACKGROUND

Autologous fat grafting (AFG) has been employed in surgical practice as a filling method. However, controversies remain on the specifics of this technique. So far, few relevant experimental large animal studies have objectively assessed factors related to AFG integration.

OBJECTIVES

This study utilized an experimental, medium-sized animal model to compare the feasibility of AFG collected employing 2 different techniques with instruments of distinct thicknesses.

METHODS

Twenty minipigs (Sus scropha domesticus) were subjected to AFG harvesting via en bloc resection utilizing 3- (Group I) and 5-mm-diameter (Group II) round punch blades (PBs) and liposuction (LS) with 3- (Group III) and 5-mm-diameter cannulas (Group IV). Both samples were grafted intramuscularly (biceps femoralis). Hematoxylin and eosin staining was employed to identify intact adipocytes, fat necrosis, fibrosis, inflammation, and oil cysts. Immunohistochemical staining (perilipin-A, tumor necrosis factor alfa, and cluster of differentiation number 31) was utilized to quantify the feasibility of adipocytes, tissue necrosis, and neoangiogenesis, respectively.

RESULTS

Hematoxylin and eosin analysis showed that fat necrosis and histiocyte presence were significantly lower in the AFG harvested utilizing a PB than in LS. For perilipin-A, a statistical difference was observed between subgroups I and III (P = 0.001) and I and IV (P = 0.004). Instrument diameter had no effect on graft integration in comparisons between groups II and III (P = 0.059) and II and IV (P = 0.132).

CONCLUSIONS

In this experimental study, fat collected utilizing a PB demonstrated higher adipocyte viability than fat collected with LS. The diameter of the collection instruments, whether PB or LS, had no effect on graft integration.

Shaping an Anatomical Breast Using Extended Latissimus Dorsi Flap and Lipofilling in Immediate Breast Reconstruction

BACKGROUND

Although many attempts have been made to augment the volume of the latissimus dorsi (LD) myocutaneous flap in breast reconstruction, only a few studies on the shaping of the LD flap to achieve a natural native breast have been conducted. We introduce our novel method to reconstruct a naturally shaped breast by combining an extended LD myocutaneous flap with immediate lipofilling.

METHODS

The patients who underwent an immediate unilateral breast reconstruction with an extended LD myocutaneous flap and lipofilling were retrospectively reviewed. The extended LD myocutaneous flap in 180-degree rotation was combined with an immediate lipofilling procedure followed by suturing to reproduce the constant dimensions of a neobreast.

RESULTS

A total of 45 patients with a mean age of 46 years and an average body mass index of 23.1 kg/m were enrolled. The average weight of the mastectomy specimens was 299.0 g. An average 18.8 × 8.7-cm skin paddle within the flap was harvested, and 71.0 mL of fat was injected into the flap. Donor site seroma was found in 9 patients, and no flap or fat necrosis was found.

CONCLUSIONS

Our technique of extended LD muscle flap with lipofilling reproduced breasts with constant dimensions and appropriate width, height, and projection. Shaping the LD muscle flap is not difficult or unpredictable. This is a simple and easy technique to shape the LD flap and will provide surgeons with an additional autologous option for breast reconstruction.

Effect of additive-assisted fat transplantation on fat graft survival rate: A preliminary experimental study based on a rabbit animal model

BACKGROUND

Improving the survival rate of fat grafts is yet a difficult problem in the field of autologous fat transplantation. Prevailing methods such as making nanofat and SVF are time-consuming. Hence, the role of additives application in the improvement of fat graft survival during fat transplantation was considered and preliminarily evaluated in a rabbit animal model.

METHODS

A rabbit animal model was established where rabbit ears were injected with a mixture of 1.5mL of adipose tissue and 1mL of saline (group A), 1.5mL of adipose tissue and 1mL of botulinum toxin A (BoNTA) (group B), 1.5mL of adipose tissue and 1mL of prostaglandin E2 (groupC), 1.5mL of adipose tissue and 1mL of PDRN (group D) respectively. Then, the extents of neovascularization and inflammation were evaluated on the 7th, 14th, 28th, 42nd, 56th and 70th day after injection by ELISA assays and H&E and immunofluorescence staining.

RESULTS

The results showed that pre-treatment with BoNTA, prostaglandin E2 and PDRN improved graft volume and weight. The H&E and immunofluorescence staining revealed that BoNTA, prostaglandin E2 and PDRN improved the graft angiogenesis. Simultaneously, TNF-α expression level detected by ELISA was the lowest in the PDRN group.

CONCLUSION

Henceforth, the present preliminary study suggests that pre-transplantation treatment with BoNTA, prostaglandin E2 and PDRN can improve the fat graft angiogenesis and graft integrity, whereby the effect of adding PDRN may be significant.

Cannula Size Effect on Stromal Vascular Fraction Content of Fat Grafts

Background

Fat is an active and dynamic tissue composed of adipocytes supported by a structural framework known as the stromal vascular fraction (SVF). SVF is traditionally isolated by enzymatic processing, but new methods are being investigated to isolate it mechanically. Recent studies propose that fat harvested with larger cannulas has a higher survival rate, most likely due to a higher concentration of SVF.

Methods

Lipoaspirates were obtained from 10 patients who underwent elective liposuction using a 5-mm and a 1-mm cannula attached to a syringe using standard pressure. The fat was aspirated from the same area at adjacent sites. An estimated 5-mm fat particles were also cut down to 1-mm using a micronizer (Marina Medical). A 5-cm³ volume of each sample was compressed through a 0.5-mm opening strainer and rinsed with normal saline to extrude the oil. The resultant SVF left on the strainer was then measured in a 1-cm³ syringe.

Results

The volume extracted from a 5-mm cannula (mean, 0.23 cm³; SD, 0.10) versus a 1-mm cannula (mean, 0.11 cm³; SD, 0.06) was statistically significant (P = 0.009). An H&E-stained slide from the SVF was obtained for confirmation. Finally, 5-mm fat particles cut down to 1-mm particles using the micronizer resulted in an average volume of 0.20 cm³, which was higher than the average volume harvested with a 1-mm cannula.

Conclusions

Harvesting with a 5-mm cannula resulted in significantly more SVF than harvesting with a 1-mm cannula. Resizing fat particles harvested with a larger cannula down to 1-mm resulted in higher SVF than SVF obtained with a 1-mm cannula directly.

Safe Composite Calf Augmentation: A Staged Procedure

BACKGROUND

Calf augmentation can be achieved by fat grafting, calf implants, or a combination of both methods (composite augmentation). For safety reasons, it is important to be aware of important calf anatomic features, specific physiologic considerations, and some health conditions that can hinder the outcome of these procedures.

OBJECTIVES

The aim of this study was to present our experience with performing composite calf augmentation, and to describe indications, surgical techniques and safety issues.

METHODS

We retrospectively analyzed 63 patients who had undergone composite calf augmentation for cosmetic and reconstructive surgery in our practice. We reviewed group demographics, complications, and results, and identified all the pitfalls encountered in our cases. Additionally, dissection of the calf regions in fresh cadavers was performed to obtain more accurate anatomy. We also measured intracompartmental pressures before and after calf augmentation with implants in 6 cases to determine pressure changes.

RESULTS

All cases received subfascial implant insertion and fat grafting as a delayed procedure. If there is a need for multiple implants, we recommend a staged procedure. Our study showed high muscle sensitivity to pressure increase after augmentation. Hence, from the standpoint of safety, we advocate subcutaneous fat grafting only. No patients developed compartment syndrome.

CONCLUSIONS

Composite calf augmentation surgery is safe and easy to reproduce, with a short recovery period and a low complication rate when done as a staged procedure and respecting specific anatomic and physiologic calf features.

LEVEL OF EVIDENCE: 4

Rhinoplasty with Fillers and Fat Grafting

Nonsurgical rhinoplasty is one choice for cases in which open surgery may be harmful, the deformity is not indicated to correct with open surgery, or in patients who have phobia of general anesthesia or any type of surgery. Autologous fat injection or fillers are most common materials currently available in the market. In this article, we explain the indications, contraindications, methods, and complications of this treatment.

Human Adipose Tissue Derivatives as a Potent Native Biomaterial for Tissue Regenerative Therapies

BACKGROUND

Human adipose tissue is a great source of translatable biomaterials owing to its ease of availability and simple processing. Reusing discardable adipose tissue for tissue regeneration helps in mimicking the exact native microenvironment of tissue. Over the past 10 years, extraction, processing, tuning and fabrication of adipose tissue have grabbed the attention owing to their native therapeutic and regenerative potential. The present work gives the overview of next generation biomaterials derived from human adipose tissue and their development with clinical relevance.

METHODS

Around 300 articles have been reviewed to widen the knowledge on the isolation, characterization techniques and medical applications of human adipose tissue and its derivatives from bench to bedside. The prospective applications of adipose tissue derivatives like autologous fat graft, stromal vascular fraction, stem cells, preadipocyte, adipokines and extracellular matrix, their behavioural mechanism, rational property of providing native bioenvironment, circumventing their translational abilities, recent advances in featuring them clinically have been reviewed extensively to reveal the dormant side of human adipose tissue.

RESULTS

Basic understanding about the molecular and structural aspect of human adipose tissue is necessary to employ it constructively. This review has nailed the productive usage of human adipose tissue, in a stepwise manner from exploring the methods of extracting derivatives, concerns during processing and its formulations to turning them into functional biomaterials. Their performance as functional biomaterials for skin regeneration, wound healing, soft tissue defects, stem cell and other regenerative therapies under in vitro and in vivo conditions emphasizes the translational efficiency of adipose tissue derivatives.

CONCLUSION

In the recent years, research interest has inclination towards constructive tissue engineering and regenerative therapies. Unravelling the maximum utilization of human adipose tissue derivatives paves a way for improving existing tissue regeneration and cellular based therapies and other biomedical applications.

Identification of the Optimal Recipient Layer for Transplanted Fat: A Prospective Study on Breast Lipoaugmentation

BACKGROUND

Fat grafting has become a popular procedure in aesthetic and reconstructive surgeries due to its safety, minimal invasiveness, and favorable visual outcomes, although the volume retention rate is unpredictable.

OBJECTIVES

A prospective clinical study on lipoaugmentation of the breast was conducted to compare fat retention rates in the pectoralis muscle and the periglandular area.

METHODS

This prospective study included 20 breasts from 11 patients who underwent primary lipoaugmentation. Volume retention rate and percentage augmentation among different recipient layers, as well as complications and patient satisfaction, were evaluated. Magnetic resonance imaging was performed preoperatively and at 1 day and 3 months postoperatively. Complications were recorded, and patient satisfaction was appraised through the use of the Breast-Q questionnaire.

RESULTS

Breasts were injected with 207 ± 29 mL of fat, achieving overall volume retention rates of 56.63% ± 16.40%. The overall augmentation was 21.53% ± 10.27%. Volume retention rate was significantly higher (59.00% ± 13.84%) in the periglandular area than in the pectoralis muscle (47.21% ± 22.41%) (P = 0.04). Augmentation was significantly higher (32.13% ± 12.96%) in the periglandular area than in the pectoralis muscle (4.95% ± 4.23%) (P = 0.00). Pain and numbness were the only reported complications. The Breast-Q score increased significantly for the measures "satisfaction with breasts," "psychosocial well-being," and "sexual well-being."

CONCLUSIONS

Fat transfer is a safe and acceptable method for aesthetic and reconstructive breast surgery. The periglandular area was a better recipient site than muscle for transferred fat.

LEVEL OF EVIDENCE: 4

Effects of Platelet-Rich Plasma on Fat and Nanofat Survival: An Experimental Study on Mice

BACKGROUND

Nanofat and fat graft survival is an important clinical problem. The authors of this study investigated whether PRP has an impact on fat and nanofat graft survival and vascularization in a mouse model.

MATERIALS AND METHODS

Fat was harvested from a 50-year-old healthy woman by vacuum suction, and nanofat was obtained by emulsification and centrifugation procedures. PRP was collected after two rounds of centrifugation from an autologous blood sample. Twenty male nude mice were divided into four treatment groups: PRP/nanofat, PRP/fat, saline/nanofat and saline/fat. After 1 month and 3 months, the grafts were extracted and weighed. The microstructure of the fat and nanofat was examined with a scanning electron microscope. HE and immunohistochemical staining was applied to observe neovascularization. Western blot analysis was used to analyse the expression of CD31 and VEGF.

RESULTS

In fat tissue, fat cells had normal connections; the fat structure was complete and fibre networks were visible. In nanofat, the extracellular matrix vascular components were visible and their structures were intact. At 1 month and 3 months, the graft weights in the PRP/fat group were significantly higher than those in the other groups. Further, a higher degree of neovascularization was observed in the PRP/nanofat group, and the expression of CD31 and VEGF in the PRP/nanofat group was higher than that in the other groups.

CONCLUSION

PRP can promote nanofat and fat graft survival and vascularization.

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 the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Quality and Quantity-Cultured Murine Endothelial Progenitor Cells Increase Vascularization and Decrease Fibrosis in the Fat Graft

BACKGROUND

Fat grafting has become a valuable technique for soft-tissue reconstruction; however, long-lasting success depends on several determinants. An early blood supply to the transplanted adipocytes is important to prevent ischemia. The recently developed quality and quantity (QQ) culture increases the vasculogenic potential of endothelial progenitor cells. The authors used a murine fat grafting model to address the hypothesis that QQ-cultured endothelial progenitor cells stimulate the establishment of a blood vessel network and increase graft success.

METHODS

c-KitSca-1Lin (KSL) cells were isolated as endothelial progenitor cell precursors from C57BL/6 mice. Adipose tissue was grafted with QQ-cultured KSL cells (QQKSL group), uncultured KSL cells (KSL group), adipose-derived stem cells (ASC group), and a combination (QQKSL+ASC group), and compared to a control group. Five and 10 weeks later, grafts were weighed, histologic and immunohistochemical parameters were evaluated, and gene expression was quantified by quantitative polymerase chain reaction.

RESULTS

The highest vessel density was observed in the combined QQKSL+ASC group (68.0 ± 4.3/mm; p < 0.001) and the QQKSL group (53.9 ± 3.0/mm; p < 0.001). QQKSL cells were engrafted in proximity to the graft vasculature. QQKSL cells decreased the fibrosis percentage (13.8 ± 1.8 percent; p < 0.05). The combined QQKSL+ASC group (22.4 ± 1.8/mm; p < 0.001) showed the fewest local inflammation units. A significant up-regulation of platelet-derived growth factor and adiponectin expression was observed in the QQKSL group and QQKSL+ASC group. Graft weight persistence was not significantly different between groups.

CONCLUSIONS

Supplementing fat grafts with quality and quantity-cultured endothelial progenitor cells improves graft quality by stimulating vascularization. The increased vessel density is associated with less fibrosis, less inflammation, and better adipose tissue integrity. Enriching fat grafts with QQ-cultured endothelial progenitor cells is a potential solution to their clinical shortcomings.

Fat Grafting Can Induce Browning of White Adipose Tissue

Background

Fat grafting is commonly used when treating soft-tissue defects. However, much of the basic biology behind fat transfer is still uncovered. Adipocytes can be divided into energy storing white and energy burning brown adipose cells. It is now well known, that also adult humans have metabolically active brown adipose tissue (BAT) within white adipose tissue (WAT). Previously our group showed that transfer of metabolically inactive WAT into a new environment increased the metabolic activity of the fat grafts to resemble the activity in the recipient site and that different WAT depots have variation in the metabolic activity. This led us to speculate, whether the metabolic increase of the graft is a result of "browning" of the transferred WAT toward beige adipose tissue.

Methods

We investigated the metabolic and histological characteristics and BAT marker Ucp1 gene expression in different types of WAT grafts placed either in subcutaneous or muscle tissue in mice. Metabolic activity of the grafts was investigated by FDG-PET/CT at 4- and 12-week time-points.

Results

The glucose uptake of all transferred fat types was increased when compared with respective control WAT regardless of transfer location. Ucp1 gene and protein expression was increased in 4 of 15 intramuscularly placed fat graft samples and showed histological resemblance to BAT with multilocular cells.

Conclusions

Grafting of metabolically inactive fat intramuscularly may induce browning of fat grafts toward more active beige adipose tissue. This opens up new research areas in exploiting fat grafting in metabolic diseases.

Gentle Is Better: The Original "Gentle Technique" for Fat Placement in Breast Lipofilling

Context

Breast lipofilling usually involves three different stages (harvesting, processing, and placement), and in each of these phases, adipocyte cells can be damaged. Our technique of fat placement is quite different from the others as we focus our attention on the last stage of fat graft procedure, which could explain the better results in graft survival.

Aims

Our method is focused on eliminating any unnecessary manipulation of the graft so as to optimize graft retention and clinical outcomes: Controlled movement and slow rate of fat injection are the cornerstone of our technique and guarantee a nontraumatic fat transfer and a greater survival rate of adipocytes.

Settings and Design

This was a retrospective cohort study.

Materials and Methods

Of 120 patients (average age 41,5 years) affected by breast soft tissue defects, 60 were managed with the lipofilling procedure using fat graft injected by "Gentle technique." To establish the effects of the injection's procedure, we compared the results obtained in fat graft maintenance with a control group made up of 60 patients, treated with fat graft injection according to Coleman procedure.

Statistical Analysis Used

Values are expressed as mean plus standard error and analyzed using Student's t test.

Results

In patients treated with Gentle technique, we observed a 60.5% + 12.5% maintenance of contour restoring and three-dimensional volume after 1 year (P < 0.0001 vs. control group); we compared the results obtained with only 39% + 4.4% of the control group treated with fat graft injected according to Coleman.

Conclusions

Controlled 26 movement and slow rate of fat injection are the cornerstone of our technique and guarantee a nontraumatic fat transfer and a greater 27 survival rate of adipocytes.

Autologous breast reconstruction using the immediately lipofilled extended latissimus dorsi flap

BACKGROUND

The latissimus dorsi flap is a popular choice for autologous breast reconstruction. To dramatically improve volume, we report our experience of using the immediately lipofilled extended latissimus dorsi (ELD) flap and show it as a valid option for autologous breast reconstruction.

METHODS

Patients undergoing the procedure between December 2013 and June 2016 were included. Demographic, clinical and operative factors were analysed, together with in-hospital morbidity and duration of postoperative hospital stay.

RESULTS

A total of 71 ELD flaps with immediate lipofilling were performed. Forty-five reconstructions were immediate and the remaining 26 delayed. Median (range) volume of autologous fat injected immediately was 171 ml (40-630 ml). Contralateral reductions were performed in 25 patients with the median reduction volume 185 g (89-683 g). Median duration of admission was 6.5 (3-18) days and patients were followed up for 12 months (1-37). Three total flap failures occurred and had to be excised (4%). One haematoma occurred requiring drainage (1%). Signs of infection requiring intravenous antibiotics occurred in five patients (7%). In 5 patients wound dehiscence occurred, and only two of these required resuturing (3%). In total, 7 patients developed a seroma requiring repeated drainage (10%). Three reconstructions experienced mild mastectomy flap necrosis with no needing reoperation (4%).

CONCLUSIONS

Our experience represents the largest series to date and shows that in carefully selected patients the technique is safe, can avoid the requirement for implants, and has the potential to streamline the reconstructive journey.

Autologous fat transfer for breast surgery

Cosmetic and reconstructive surgeries always have a primary aim of the best outcome for the patient, with a big emphasis on the aesthetics. Lipomodelling is one such technique, originally described over a century ago but still used to this day, to provide a patient with the highest quality results. This is particularly true for lipomodelling of the breast, whether it be purely cosmetic, or for a post-mastectomy reconstruction for a breast cancer patient. Lipomodelling provides an effective way of restoring and even improving the look and aesthetics of the breast and of helping achieve the patient's expectations. With the added advantage of being autologous, the procedure is safe and effective. This review discusses the latest guidelines and literature on autologous lipomodelling.

Botulinum toxin A improves adipose tissue engraftment by promoting cell proliferation, adipogenesis and angiogenesis

Adipose tissue engraftment has become a well-established therapy in plastic and reconstructive surgery used to restore age-related or injury-related soft tissue loss. However, the unpredictable absorption rates limit its further application. Some clinicians have noted that more optimal aesthetic results are achieved when botulinum toxin A (BoNTA) is applied prior to adipose tissue grafting. In the present study, we transplanted allogeneic adipose tissue treated with or without BoNTA in SD rats in vivo. We subsequently evaluated the survival rate (weight, volume, apoptosis and cellular integrity) and revascularization of the adipose tissue. The results revealed that BoNTA improved the long-term weight and volume retention of the graft, and preserved cellular integrity. BoNTA significantly increased the expression levels of CD31 and vascular endothelial growth factor (VEGF), suggesting enhanced vasodilation and endothelial cell proliferation. In vitro, adipose-derived stem cells (ASCs) were isolated, identified and induced to proliferate and differentiate with or without BoNTA. Furthermore, to evaluate the proliferative, adipogenic and angiogenic ability of the ASCs, CCK-8 assay and Oil Red O staining were conducted. Gene and protein expression levels were analyzed by RT-qPCR and western blot analysis. The results revealed that 8×10⁻² U/ml BoNTA as the optimal dose increased ASC proliferation and adipogenic differentiation capacity, as well as the expression level of the key cytokine of angiogenesis. On the whole, our findings indicate that BoNTA improves adipose tissue engraftment and promotes ASC regeneration, which could benefit future clinical applications.

Bone marrow mesenchymal stem cell‑derived extracellular vesicles improve the survival of transplanted fat grafts

Autologous fat grafting is a promising surgical technique for soft tissue augmentation, reconstruction and rejuvenation. However, it is limited by the low survival rate of the transplanted fat, due to the slow revascularization of such grafts. Previous studies have demonstrated that bone marrow mesenchymal stem cell-derived extracellular vesicles (BMSC-EVs) are proangiogenic. The present study aimed to investigate whether BMSC-EVs could improve the survival of transplanted fat grafts. Extracellular vesicles were isolated from the supernatant of cultured rat bone marrow mesenchymal stem cells, and characterized by flow cytometry and scanning electron microscopy. Their proangiogenic potential was measured in vitro using tube formation and cell migration assays. Subsequently, human fat tissue grafts, alongside various concentrations of BMSC-EVs, were subcutaneously injected into nude mice. A total of 12 weeks following transplantation, the mice were sacrificed and the grafts were harvested. The grafts from the experimental group had a higher survival rate and an increased number of vessels compared with grafts from the control group, as demonstrated by tissue volume, weight and histological analyses. Reverse transcription-quantitative polymerase chain reaction analysis indicated that the expression levels of proangiogenic factors were increased in the experimental group compared with in the control group, thus suggesting that BMSC-EVs may promote neovascularization by stimulating the secretion of proangiogenic factors. The present study is the first, to the best of our knowledge, to demonstrate that supplementation of fat grafts with BMSC-EVs improves the long-term retention and quality of transplanted fat.

Adipose-derived mesenchymal stem cells promote the survival of fat grafts via crosstalk between the Nrf2 and TLR4 pathways

Autologous fat grafting is an effective reconstructive surgery technique; however, its success is limited by inconsistent graft retention and an environment characterized by high oxidative stress and inflammation. Adipose-derived stem cells (ADSCs) increase the survival of fat grafts, although the underlying mechanisms remain unclear. Here, TLR4^−/− and Nrf2^−/− mice were used to explore the effects of oxidative stress and inflammation on the viability and function of ADSCs in vitro and in vivo. Enrichment of fat grafts with ADSCs inhibited inflammatory cytokine production, enhanced growth factor levels, increased fat graft survival, downregulated NADPH oxidase (NOX)1 and 4 expression, increased vascularization and reduced ROS production in a manner dependent on toll-like receptor (TLR)-4 and nuclear factor erythroid 2-related factor 2 (Nrf2) expression. Immunohistochemical analysis showed that exposure to hypoxia enhanced ADSC growth and promoted the differentiation of ADSCs into vascular endothelial cells. Hypoxia-induced inflammatory cytokine, growth factor and NOX1/4 upregulation, as well as increased ROS production and apoptosis in ADSCs were dependent on TLR4 and Nrf2, which also modulated the effect of ADSCs on promoting endothelial progenitor cell migration and angiogenesis. Western blot analyses showed that the effects of hypoxia on ADSCs were regulated by crosstalk between Nrf2 antioxidant responses and NF-κB- and TLR4-mediated inflammatory responses. Taken together, our results indicate that ADSCs can increase the survival of fat transplants through the modulation of inflammatory and oxidative responses via Nrf2 and TLR4, suggesting potential strategies to improve the use of ADSCs for cell therapy.

Maximizing the Volume of Latissimus Dorsi Flap in Autologous Breast Reconstruction with Simultaneous Multisite Fat Grafting

BACKGROUND

The pedicled latissimus dorsi (LD) flap serves an important function in breast reconstruction, but its utility is limited by its inability to provide sufficient breast volume.

OBJECTIVES

The purpose of this preliminary report was to review the techniques and outcomes of utilizing fat-grafted, volume-enhanced LD flap transfer with fat grafting recipient sites in autologous breast reconstruction.

METHODS

A retrospective study was performed of 10 patients (14 breasts) who underwent autologous breast reconstruction utilizing the LD flap transfer technique and simultaneous fat grafting between August 2012 and September 2014. Multilayer, multisite fat grafting was performed to the LD muscle, LD skin paddle, mastectomy skin flaps, and the pectoralis major and serratus muscles simultaneously with the LD flap transfer.

RESULTS

Three patients underwent an immediate breast reconstruction, four underwent a delayed breast reconstruction, and four underwent a tertiary breast reconstruction following previously failed breast reconstructions (one patient underwent each of the first two procedures, one on each breast). The average age of the patients was 55 years (range, 39-76 years), the average body mass index of the patients was 29.3 (range, 19.6-39.9), and the average fat grafting volume for the patients was 176 mL (range, 50-300 mL). There was 100% flap survival and complete wound healing. No seroma or fat grafting-related complications were clinically detected. Three patients required additional fat grafting.

CONCLUSIONS

The fat-grafted, volume-enhanced LD flap procedure with fat grafting recipient sites offers a simple and safe technique for autologous breast reconstruction, with low morbidity and fast recovery. It can be a useful alternative to utilizing abdomen-based flaps in autologous breast reconstruction or could be performed to salvage both implant-based and free-flap breast reconstructions. LEVEL OF EVIDENCE 4: Therapeutic.

The effect of combined use of platelet-rich plasma and adipose-derived stem cells on fat graft survival

BACKGROUND

Free fat grafts have an unpredictable survival rate that limits their successful use. To increase the viability of fat grafts, it is important to minimize the reabsorption rate.

OBJECTIVE

Our aim was to investigate whether the combined use of platelet-rich plasma (PRP) and adipose derived stem cells (ADSCs) would contribute an improvement in lower resorption rates of fat grafts.

METHODS

Inbred Fischer 344 rats were randomized into 4 groups (n = 10). Fat grafts were mixed with Dulbecco modified Eagle medium in group A, with PRP in group B, with ADSC in group C, and with PRP + ADSC in group D and were injected to the scalp.In vitro growth factor (vascular endothelial growth factor, transforming growth factor-β, and fibroblast growth factor) levels were compared using enzyme-linked immunoassay method. After 12 weeks weight, volume and histology of the transplants were evaluated.

RESULTS

The mean weight and volume of the fat grafts were highest in group D. Histopathological investigations revealed that the number of viable adipocytes and blood vessels were highest in group D. The level of growth factors was significantly higher in stem cell plus PRP group.

CONCLUSION

Adipose-derived stem cells combined with PRP can enhance the survival of transplanted fat tissue.

Power-assisted gluteal augmentation: a new technique for sculpting, harvesting, and transferring fat

BACKGROUND

A simple and reproducible surgical technique for gluteal shaping and augmentation with autologous fat is needed.

OBJECTIVES

The authors describe a novel approach to large-volume gluteal augmentation that combines power-assisted liposculpting and fat harvesting of the zones around the buttock with autologous fat transfer.

METHODS

One hundred ten patients who underwent gluteal augmentation were evaluated in a prospective study. Liposculpting and fat harvesting were performed with power-assisted liposuction. Fat then was transferred to the gluteal region with simultaneous power-assisted vibration and tunnelization. A questionnaire to assess patient satisfaction was administered at 6 months postoperatively.

RESULTS

The mean body mass index of the patients was 30 kg/m(2) (range, 26-36 kg/m(2)). Liposuction volumes ranged from 1400 to 5000 mL, and injection volumes ranged from 300 to 900 mL per side for each session. Operating times ranged from 60 to 120 minutes. Patients were monitored for an average of 20 months (range 12-48 months). Complications included a burning sensation in 5 of 110 patients (4.5%), persistent swelling in the lower back in 3 patients (2.7%), and a mild infection in 1 patient (0.9%).

CONCLUSIONS

Power-assisted gluteal augmentation with autologous fat is an efficient, safe, and reproducible procedure that produces an aesthetically pleasing gluteal projection and contour.

LEVEL OF EVIDENCE

4 Therapeutic.

Stromal vascular fraction: A regenerative reality? Part 1: Current concepts and review of the literature

Stromal Vascular Fraction (SVF) is a heterogeneous collection of cells contained within adipose tissue that is traditionally isolated using enzymes such as collagenase. With the removal of adipose cells, connective tissue and blood from lipoaspirate, comes the SVF, a mix including mesenchymal stem cells, endothelial precursor cells, T regulatory cells, macrophages, smooth muscle cells, pericytes and preadipocytes. In part 1 of our 2-part series, we review the literature with regards to the intensifying interest that has shifted toward this mixture of cells, particularly due to its component synergy and translational potential. Trials assessing the regenerative potential of cultured Adipose Derived Stem Cells (ADSCs) and SVF demonstrate that SVF is comparably effective in treating conditions ranging from radiation injuries, burn wounds and diabetes, amongst others. Aside from their use in chronic conditions, SVF enrichment of fat grafts has proven a major advance in maintaining fat graft volume and viability. Many SVF studies are currently in preclinical phases or are moving to human trials. Overall, regenerative cell therapy based on SVF is at an early investigative stage but its potential for clinical application is enormous.

Immediate Large-Volume Grafting of Autologous Fat to the Breast Following Implant Removal

BACKGROUND

To optimize autologous breast augmentation, a simple and reproducible surgical approach that maximizes the volume of fat transferred to the breast while minimizing the number of sessions and the operating time is needed.

OBJECTIVES

The authors describe a novel approach for large-volume fat grafting to the expanded skin and subcutaneous tissue of the breast immediately after explantation, exchanging the volume provided by the implants with transplanted fat in a single session.

METHODS

Eighty patients (160 breasts) undergoing explantation and autologous fat transfer were evaluated in a prospective study. Fat was harvested with the lipomatic power-assisted liposuction machine (Lipomatic Eva SP, Euromi SA, Verviers, Belgium) and was injected with simultaneous vibration and tunnelization of the recipient site by means of the same machine with suction disabled. Changes in breast volume were measured in terms of bra cup size, and patients were monitored by mammography and ultrasonography. Patient satisfaction was assessed with a questionnaire administered 6 months postoperatively.

RESULTS

Injected fat volumes ranged from 300 to 600 mL per breast. Operating times ranged from 45 to 90 minutes. For all patients, one injection session was sufficient to replace the volume of the previous implant. Patients were monitored for an average of 2 years, and complications included cyst formation in 9 of 160 breasts (5.6%) and infection in 2 breasts (1.25%).

CONCLUSIONS

Power-assisted transfer of autologous fat to the breast improves the ability of the recipient site to receive the graft and allows for explantation and fat transplantation in a single session. This approach is suitable for patients who desire a natural-appearing breast that is similar in volume to their previous implant.

Does water-jet force make a difference in fat grafting? In vitro and in vivo evidence of improved lipoaspirate viability and fat graft survival

BACKGROUND

Recent literature has revealed that water-jet-assisted liposuction offers a new method of conventional liposuction techniques by using the gentle spray of fluid. However, there has not yet been a systematic, randomized, controlled study to demonstrate its effect on the vitality and postoperative fat survival of fresh lipoaspirates. In this study, the authors compared liposuction with or without water-jet assistance in a blinded fashion.

METHODS

Human lipoaspirates were obtained from healthy Chinese female volunteers for body shaping. Lipoaspirates were harvested by a single surgeon using the same material and machine; water-jet assistance was the only variance in this study. At the beginning of surgery, the authors randomly performed conventional manual liposuction without water-jet assistance for one side to obtain 50 ml of lipoaspirate (group B). At the corresponding area of the other side, the authors used water-jet-assisted liposuction to obtain another 50 ml of lipoaspirate (group A). All of the harvested lipoaspirates were used in the in vitro and in vivo experiments to evaluate the effect of water-jet force on the vitality and postoperative fat survival of fresh lipoaspirates.

RESULTS

Fresh lipoaspirates from group A had greater viability and a higher percentage of CD34/CD45 cells than group B. Grafted lipoaspirates in group A had better weight retention, less apoptosis, and greater angiogenesis.

CONCLUSIONS

The fate of grafted lipoaspirates was affected by water-jet force. With the assistance of water-jet force during the harvesting procedure, the authors could obtain more viable lipoaspirates and achieve better fat survival.

Fat Graft Viability in the Subcutaneous Plane versus the Local Fat Pad

Background:

Fat grafting has been increasingly utilized in both aesthetic and reconstructive surgical procedures, yet the basic scientific understanding of fat grafting has lagged behind the pace of clinical innovation and utilization. This lack of basic scientific understanding has perhaps manifested itself in the wide range of graft viability reported across the literature. This study attempts to further the underlying mechanisms of fat graft take and viability through the comparison of the subcutaneous plane and the local fat pad in athymic rats.

Methods:

Lipoaspirate from a consenting patient was grafted into 2 locations in the subcutaneous plane and into the 2 inguinal fat pads in each of 4 athymic rats. Specimens were then collected after 47 days, and immunohistochemistry was utilized to determine angiogenesis in the fat grafts as a measure of fat graft take. Data were analyzed using the Student’s t test and analysis of variance followed by multiple comparisons.

Results:

There was no statistically significant difference (P = 0.2913) between the inguinal fat pad and the subcutaneous plane when measuring neovascularization. Analysis of variance comparing the graft locations also indicated no statistically significant difference when comparing each of the rats.

Conclusions:

Investigation into fat graft injection location indicates that there is no statistically significant difference in angiogenesis signals between the subcutaneous plane and the local fat pad in the athymic rat model. Further research should aim to continue to close the gap between clinical practice and basic scientific understanding of fat grafting.

Effects of the diabetic condition on grafted fat survival: an experimental study using streptozotocin-induced diabetic rats

Background

Autologous fat grafts have been widely used for cosmetic purposes and for soft tissue contour reconstruction. Because diabetes mellitus is one of the major chronic diseases in nearly every country, the requirement for fat grafts in diabetes patients is expected to increase continuously. However, the circulation complications of diabetes are serious and have been shown to involve microvascular problems, impairing ischemia-driven neovascularization in particular. After injection, revascularization is vital to the survival of the grafted fat. In this study, the authors attempted to determine whether the diabetic condition inhibits the survival of injected fat due to impaired neovascularization.

Methods

The rat scalp was used for testing fat graft survival. Forty-four seven-week-old male Sprague-Dawley rats were allocated to a diabetic group or a control group. 1.0 mL of processed fat was injected subcutaneously into the scalp of each rat. The effect of diabetes was evaluated by calculating the volume and the weight of the grafted fat and by histologically analyzing the fat sections.

Results

The surviving fat graft volume and weight were considerably smaller in the diabetic group than in the control group (P<0.05), and histological evaluations showed less vascularity, and more cysts, vacuoles, and fibrosis in the diabetic group (P<0.05). Cellular integrity and inflammation were not considerably different in the two groups.

Conclusions

As the final outcome, we found that the presence of diabetes might impair the survival and the quality of fat grafts, as evidenced by lower fat graft weights and volumes and poor histologic graft quality.

Improvement in autologous human fat transplant survival with SVF plus VEGF-PLA nano-sustained release microspheres

Early neovascularization is important for autologous fat transplant survival. SVF cells are ideal seed cells. Both vascular endothelial growth factor (VEGF) and SVF cells can promote neovascularization. However, the half-life (about 50 min) of VEGF is too short to sustain an adequate local concentration. We have investigated whether VEGF-polylactic acid (PLA) nano-sustained release microspheres plus SVF cells can improve neovascularization and survival of transplanted fat tissues. SVF cells were harvested and constructed VEGF-PLA nano-sustained release microspheres in vitro. Human fat tissues was mixed with SVF cells plus VEGF-PLA, SVF cells alone or Dulbecco's modified Eagle's medium as the control. These three mixtures were injected into random sites in 18 nude mice. Two months later, the transplants were weighed and examined histologically; and capillaries were counted to quantify neovascularization. Hematoxylin-eosin (HE) and anti-VEGF stains were applied to reveal cell infiltration. The mean wet weight of fat in the SVF plus VEGF-PLA, SVF alone, and control transplants were 0.18 ± 0.013 g, 0.16 ± 0.015 g, and 0.071 ± 0.12 g, respectively; the differences between groups were statistically significant. More vessels were present in the SVF plus VEGF-PLA transplants than in the other two types. Transplants mixed with SVF cells also had an acceptable density of capillaries. Histological analysis revealed that both the SVF plus VEGF-PLA and SVF alone transplants, but not the control transplants, were composed of adipose tissue, and had less fat necrosis and less fibrosis than control specimens. SVF plus VEGF-PLA transplants had significantly greater capillary density and VEGF expression than the other two transplant groups. Thus transplanted fat tissue survival and quality can be enhanced by the addition of VEGF-PLA nano-sustained release microspheres plus SVF cells.

Histological findings of an autologous dermal fat graft implanted onto the pectoralis major muscle of a rat model

Background

The aim of this study was to investigate the maintenance of volume as a spacer by comparing vascular supply and apoptosis in an implanted autologous-free dermal fat graft (FDFG) and free fat graft (FFG). An autologous FDFG is a material used in plastic surgery and oncoplastic breast surgery that is ideal for immediate volume replacement after partial mastectomy because of its easy availability and minimal invasion of the donor site; however, immunohistochemical findings and survival procedures have not yet been reported.

Methods

An experimental protocol using a unique animal model was designed for the present study. The expression of vascular endothelial growth factor (VEGF) was measured in FDFGs and FFGs implanted onto the pectoral major muscle of Wistar rats. Thirty Wistar rats were divided into two groups and postoperatively 1, 2, 4, 8, and 16 weeks (POW1, 2, 4, 8, 16). Six samples from three rats in each group were used as control samples (POW0).

Results

The thickness of the implanted FDFG was not significantly different from the control sample at POW1, 2, 4, 8, and 16 between FDFG and FFG group; however, the thickness at POW8 and 16 was significantly lesser in the FFG group than in the control samples.

The average proportion of fatty tissue to whole tissue ranged from 34.2 to 48.6 % in the FDFG group and from 57.2 to 76.7 % in the FFG group during the observation period; however, there was no significant difference in the proportion of fatty tissue between these two groups. There were no significant differences between the average number of VEGF-positive cells in the FDFG group and the FFG group at POW1, 2, 4, 8, and 16. The average number of TUNEL-positive cells in the early period at POW1 was significantly lower in the FDFG group than in the FFG group.

Conclusions

This rat model was useful for investigating the mechanisms of angiogenesis, apoptosis, structure maintenance, and fibromatous changes. From the present experimental study, we believe that FDFG is one of the most convenient materials currently available to repair small defects at the time of BCS even in the clinical field.

Transient overexpression of Pparγ2 and C/ebpα in mesenchymal stem cells induces brown adipose tissue formation

BACKGROUND

Brown adipose tissue plays a pivotal role in mammal metabolism and thermogenesis. It has a great therapeutic potential in several metabolic disorders such as obesity and diabetes. Mesenchymal stem cells (MSCs) are suitable candidates for brown adipose tissue formation de novo. Pparγ2 and C/ebpα are nucleic receptors known to mediate adipogenic differentiation. We hypothesized that overexpression of the Pparγ2 and C/ebpα genes in MSCs would lead to the formation of adipose tissue.

MATERIALS & METHODS

MSCs bearing the Luc reporter gene were transfected to overexpress Pparγ2 and C/ebpα. Differentiation of nucleofected cells was evaluated in vitro and in vivo following ectopic implantation of the cells in C3H/HeN mice.

RESULTS

After implantation, the engineered cells survived for 5 weeks and brown adipose-like tissue was observed in histological samples. Immunostaining and bioluminescent imaging showed new adipocytes expressing Luc and the brown adipose tissue marker, UCP1, in vitro and in vivo.

CONCLUSION

We show that gene delivery of transcription factors into MSCs generates brown adipose tissue in vitro and in vivo.

Fat Ful'fill'ment: A Review of Autologous Fat Grafting

For more than a century, clinicians have attempted to utilise fat for the treatment of tissue deficiencies and contour abnormalities. Autologous fat transplantation for soft-tissue augmentation has become increasingly popular in recent years. The popularity of tumescent liposuction has brought renewed interest and accessibility of fat for transplantation. Newer techniques and approaches to augmentation have provided more predictable and reproducible results. Fat augmentation has become an effective, safe and reliable method for restoring volume and correcting the atrophy that accompanies senescence. In this review, the authors have described their approach to fat transplantation.

Stromal vascular fraction (SVF) cells enhance long-term survival of autologous fat grafting through the facilitation of M2 macrophages

Optimum perfusion may be the key to the endurance, and hence survival, of autologous adipose tissue transportation. Stromal vascular fraction (SVF) cell therapy can greatly improve the survival of fat grafts by enhancing angiogenesis. However, SVF cells are poorly retained in later stages of SVF-assisted adipose tissue transplant. Therefore, it hardly defines the angiogenic effect through long-term transportation. Adipose tissue suffers from acute hypoxia in the early stage of transportation, leading to the recruitment of macrophages. M2 macrophages enhance angiogenesis in adipose transplantation by acting as an angiogenic signal source, promoting tip cell migration and assisting tip cell fusion. Furthermore, the angiogenic and anti-inflammatory micro-environment in the graft created by M2 macrophages may stimulate the transformation of infiltrating macrophages to M2 macrophages. These M2 macrophages may enhance the long-term retention of graft through angiogenesis. Based on these observations, we postulate that the long-term angiogenic effect of SVF cells may be achieved through the facilitation of the M2 macrophages.