Bioactivation of free-fat transfers: a potential new approach to improving graft survival

Non-Surgical Touch-Up with Hyaluronic Acid Fillers Following Facial Reconstructive Surgery

The use of hyaluronic acid (HA) injectable fillers has become increasingly widespread in facial recontouring and rejuvenation. We report our experiences to emphasize the role of HA fillers as tools beyond aesthetic treatments in cases of post-surgical facial sequelae. HA fillers are generally used for aesthetic rejuvenation, but one potential new horizon could be their application in trauma, reconstructive, and craniofacial surgery. This study was conducted retrospectively, evaluating medical reports of patients treated at the Maxillofacial Surgery Unit, University of Campania “Luigi Vanvitelli”, Naples, for lip incompetence, trauma, oncological, reconstructive, and craniosynostosis surgery sequelae. Visual analog scale (VAS) evaluation was performed to assess patient satisfaction. No major complications (i.e., impending necrosis or visual loss) were reported. Bruising and swelling was reported for 48 h after lip injection. At the immediate VAS evaluation, 67% of the patients were “extremely satisfied” and 33% “satisfied”. In those 33%, VAS scores changed to “extremely satisfied” at 6–9 weeks and 3–6 months of VAS evaluation (contextually to improvement in tissue flexibility, elasticity, and aesthetic appearance). Results indicate that this minimally invasive approach achieves a high level of aesthetic enhancement, improving patient satisfaction. The concept of HA filler applications could be a frontier that may be applicable to other areas of reconstructive facial plastic surgery.

The significance of erythropoietin and insulin administration on survival of fat tissue after autologous fat transplantation in Wistar rats. An experimental study

Autologous fat transfer is widely used by plastic surgeons for aesthetic and reconstructive purpose, but it has a great disadvantage because of its high variability rate of resorption. Numerous studies have examined the use of different agents to increase the viability of fat grafts. The results were discouraging because the use of a single angiogenic factor to stimulate fat graft angiogenesis may be inappropriate. We proposed to use two pharmacological factors, erythropoietin (EPO) and insulin (INS), in order to decrease the resorption rate, to improve graft vascularization, and to reduce the number of complications. Twenty-four Wistar male rats were randomly divided in four groups (I–IV) of six animals each. The rats belonging to control group were given autologous transfer of simple fat. In group II, the graft was improved with EPO, in group III with INS, and in group IV both pharmacological agents were administered. Histological evaluation of the grafts at two months after injection demonstrated adipocyte survival in all four groups. The volume of the graft has progressively decreased in all groups and the difference in graft volume at one and two months after transplantation was not significant. The highest maintenance of fat graft volume (95%) at two months was observed in group IV, followed by group II and group III. Necrotic cystic changes and increased fibrosis were most extensive in the control group. The combination of INS with EPO may have a synergistic and additive effect. Efficient administration and dose optimization of these growth factors are important things to consider in the future.

Fat Graft Enrichment Strategies: A Systematic Review

BACKGROUND

Autologous fat grafting is a dynamic modality used in plastic surgery as an adjunct to improve functional and aesthetic form. However, current practices in fat grafting for soft-tissue augmentation are plagued by tremendous variability in long-term graft retention, resulting in suboptimal outcomes and repetitive procedures. This systematic review identifies and critically appraises the evidence for various enrichment strategies that can be used to augment and improve the viability of fat grafts.

METHODS

A comprehensive literature search of the Medline and PubMed databases was conducted for animal and human studies published through October of 2017 with multiple search terms related to adipose graft enrichment agents encompassing growth factors, platelet-rich plasma, adipose-derived and bone marrow stem cells, gene therapy, tissue engineering, and other strategies. Data on level of evidence, techniques, complications, and outcomes were collected.

RESULTS

A total of 1382 articles were identified, of which 147 met inclusion criteria. The majority of enrichment strategies demonstrated positive benefit for fat graft survival, particularly with growth factors and adipose-derived stem cell enrichment. Platelet-rich plasma and adipose-derived stem cells had the strongest evidence to support efficacy in human studies and may demonstrate a dose-dependent effect.

CONCLUSIONS

Improved understanding of enrichment strategies contributing to fat graft survival can help to optimize safety and outcomes. Controlled clinical studies are lacking, and future studies should examine factors influencing graft survival through controlled clinical trials in order to establish safety and to obtain consistent outcomes.

Impact of growth factor content on proliferation of mesenchymal stromal cells derived from adipose tissue

Autologous adipose tissue (AT) transfer has gained widespread acceptance and is used for a broad variety of regenerative clinical indications. It is assumed that the successful outcome of AT transfer essentially depends on the amount of autocrine-generated growth factors (GF). It is supposed that several GF enhance and improve the anatomic and functional integration of the transplanted AT grafts at the site of implantation. In the present study we have investigated for the first time the correlation between the concentration of GF of freshly isolated AT and the proliferation and migration capacity of mesenchymal stroma cells (MSCs) derived from the respective AT sample. We here show that the proliferation and migration capacity of MSCs strongly depends on the GF content of the AT the cells were isolated from but in an inversely proportional manner. The lower the GF content of an AT sample was, the higher was the proliferation and migration capacity of the respective MSC population contained in the AT and vice versa. Furthermore, we found that supplementation with recombinant GFs only in the case of AT samples with low but not with higher growth factor contents led to a significant enhancement of proliferation and migration of the AT-resident MSCs. As we further show, this inefficiency of GFs to enhance MSC proliferation and migration in AT samples with high GF contents indicates a GF-mediated negative feedback mechanism leading to an impaired GF signaling in MSC obtained from those AT samples. Our results might explain why the successful use of AT grafting is frequently limited by low and unpredictable survival rates, and we suggest to use the knowledge of GF content of harvested AT as a predictive clinical parameter for risk assessment of the therapeutic outcome of autologous AT transfer.

A Study of the Effect of Platelet-Rich Plasma on Outcomes After Aspirated Human Fat Grafting With Experimental Design

INTRODUCTION

Over the past decade, some studies have focused on whether platelet-rich plasma (PRP) can promote the survival of fat grafts after transplantation. However, the results of these studies have been controversial because of the variations in research methods and assessment methodologies.

METHODS

In this study, the authors aspirated fat particles from the abdomen of a healthy woman, mixed them with PRP, and injected them into the backs of nude mice subcutaneously, which simulates the clinical model. The control group was designed to mix aspired fat with normal saline. The fat grafts were removed 10 weeks after transplantation, stained with hematoxylin and eosin, and sliced into pathological sections, which were subsequently scanned and analyzed using the Digital Slide Scanning System (PRECICE, Beijing, China).

RESULTS

The total area of the graft section and the necrotic adipose tissue area in the control group were significantly larger than that in the PRP group. The fibrosis tissue area in the PRP group was significantly larger than that in the control group. There were no statistically significant differences in the viable adipocyte area, the cyst area, and the mature blood vessel number between the PRP and control groups.

CONCLUSION

In this study, PRP did not cause an increase in the number of viable adipocytes; however, it did increase the amount of inflammation, which promoted necrotic tissue absorption and the proliferation of granulation tissue. Further research, including research on normalization of fat preparation and grafting, unification of the PRP preparation and application scheme, and optimization of histological measurement and analysis methods, is needed to assess the effect of PRP on fat grafting.

Adipokine concentrations in lipoaspirates may have a role in wound healing

OBJECTIVES

In addition to its use as a volume filler, fat grafting may have a potential role in wound healing based on the concentration of growth factors in the lipoaspirate. In this study, we compare the quantitative and qualitative concentration of the various growth factors and adipokines using the Shippert or the Coleman techniques to prepare the lipoaspirate.

METHODS

We measured leptin, adiponectin and the growth factors, i.e., acidic fibroblast growth factor (aFGF), basic FGF (bFGF), keratinocyte growth factor (KGF), bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) by ELISA in solid and liquid fractions obtained with both techniques in human fat obtained with Coleman technique and Shippert technique.

RESULTS

All of these peptides, except BMP-2, were detected in relevant quantities in the solid fraction. The Coleman but not the Shippert technique resulted in statistically higher adiponectin concentrations in the solid tissue fraction. The other four growth factors occurred in significantly higher concentrations in the solid fractions compared to the liquid fractions, independent of the processing technique.

CONCLUSION

In summary, we demonstrated that KGF, aFGF, bFGF and VEGF, as well as leptin and adiponectin, are contained in fat suspensions obtained by liposuction and in the supernatant. Only the concentration of adiponectin was in the range reported to contribute to wound healing.

Efficacy of Platelet-Rich Plasma on Fat Grafts in the Repair of Tympanic Membrane Perforations: An Experimental Study

OBJECTIVE

We investigated the use of autologous platelet-rich plasma (PRP) to improve the success rate of fat graft myringoplasty in perforated tympanic membranes of rats.

MATERIALS AND METHODS

A total of 20 healthy Wistar albino female rats were divided into two groups. In Group 1, the left tympanic membranes were perforated and grafted with a fat graft that was harvested from the inguinal region. In Group 2, the left tympanic membranes were perforated, and a fat graft was also harvested from the inguinal region. Then, the fat was soaked in 0.5 mL PRP and grafted at the perforation. After the procedure, the rats were examined, and the graft situation was assessed at 3, 5, 7, 10, and 14 days. All of the rats were sacrificed 21 days after perforation, and a histopathological examination was made.

RESULTS

We compared fat graft histopathological and otomicroscopic findings between the groups. While we did not observe graft rejections in Group 2, we saw 1 case of graft rejection in Group 1. In the histopathological examination, PRP prevents fat graft resorption by the terms of the adipocyte area, granulation tissue area, and vacuolization area.

CONCLUSION

This study demonstrated the efficacy of fat grafts prepared with PRP on rat tympanic membranes. The fat graft with PRP did not statistically improve the success rate compared to the graft without PRP. Histopatologic findings of the study showed that PRP prevents fat graft resorption. Further studies are needed to further examine the advantages of the graft with PRP.

Application of Epineural Sheath as a Novel Approach for Fat Volume Maintenance

INTRODUCTION

Various methods have been suggested to improve fat graft survival and decrease graft loss. The exact mechanism of fat graft survival is still unclear, and new strategies are needed to further investigate it.

MATERIALS AND METHODS

The efficacy of epineural sheath in fat volume maintenance was tested in rat model. Five experimental groups were created: group 1, fat graft without any coverage; group 2, epineural sheath tube alone; group 3, epineural sheath tube filled with fat graft; group 4, fat graft mixed with minced epineural sheath without any coverage; and group 5, fat graft covered with the epineural sheath patch. All grafts were implanted into the dorsal subcutaneous region and were followed for up to 12 weeks, when samples were harvested for hematoxylin and eosin and immunostaining for vascular endothelial growth factor expression and perilipin evaluation of fat viability.

RESULTS

In groups 1 and 4, over 25% of graft loss was observed at first week, over 50% at third week, and 100% at sixth week postimplantation. The weight of fat graft within the epineural sheath tube and the weight of epineural tube (ET) alone were maintained up to 12 weeks postimplantation. The weight of fat graft within the epineural patch was maintained up to 6 weeks, but 50% of weight loss was observed between 6 and 12 weeks. Structure of the epineural sheath tubes and patches was intact, and no leakage of fat graft was observed. Based on hematoxylin and eosin staining, normal structure and integrity of the fat graft within the ET were preserved up to 12 weeks postimplantation. Characteristic adipocyte morphology was confirmed by perilipin staining, showing viable fat cells in groups 3 and 5 at 12 weeks. Increased vascular endothelial growth factor expression was observed in groups 2, 3, 4, and 5.

CONCLUSIONS

Both, the ETs and epineural patches maintained 100% and 50% of fat graft weight at 12 weeks postimplantation, respectively. These results were confirmed by histology and immunostaining showing viable adipocytes within the epineural patches (6 weeks) and tubes (12 weeks). These results are encouraging and justify further evaluation of fat volume maintenance in preclinical large animal model in preparation to clinical application.

Platelet-Rich Plasma (PRP) Utilized to Promote Greater Graft Volume Retention in Autologous Fat Grafting

Objectives:

Autologous fat theoretically provides one of the most ideal mediums for soft-tissue augmentation and reconstruction, although its clinical applications have been marked with skepticism because of its documented unreliable survival. Over the years, numerous unsuccessful efforts have set forth to elucidate modifications in the application process of autologous fat grafts to allow the medium greater clinical predictability. This study aims to investigate the effects of platelet-rich plasma (PRP) on autologous fat grafts when used in conjunction with each other in soft tissue augmentation and reconstruction.

Study Design:

Retrospective review, over a 30-month period, of consecutive patients with results greater than 6 months in duration.

Methods:

This study is based on clinical experiences representing 2033 grafts in 448 consecutive patients using PRP additives and in the previous 132 patients who had syringe harvest without use of PRP. All PRP isolates were harvested via the Smart Prep system. Harvest and augmentation techniques are discussed and representative results are presented.

Results:

Results were based on clinical observations and patient satisfaction. Of the 580 patients in the experimental group, essentially all showed greater graft volume retention over extended time intervals compared with control subjects (nongraft areas). Patients in the PRP-added experimental group displayed less postoperative ecchymosis and edema, which also led to greater patient satisfaction in this group.

Conclusion:

Adding PRP to autologous fat aids in graft volume retention and survival when used clinically for soft-tissue augmentation and reconstruction.

The Viability of Human Adipocytes after Closed-Syringe Liposuction Harvest

The notion of free-tissue transplantation of autologous adipose is not new, but has experienced a resurgence in interest due to the popularity of liposuction surgery. Literature review indicates a lack of predictability with previously described techniques, and various theories have been proposed to explain clinical findings. A requisite premise of autologous soft-tissue transplantation is that the tissue must survive the harvest. Recent advances in cell culture technique have allowed us to prove that adipocytes can survive harvesting by aspiration, at least by the method used in this investigation. A surprising finding was that the adipocytes maintained a mature phenotype in culture. This may provide a laboratory model for further investigation.

Autologous Fat Transfer: Eliminating the Centrifuge, Decreasing Lipocyte Trauma and Establishing Standardization for Scientific Study

Introduction:

The autologous fat transfer procedure has undergone a renewal of interest because of the need for larger quantities of economical filler (face, buttocks, hands, and breasts). Commercial fillers are cost prohibitive when large quantities are needed. Present instruments on the market are not specialized enough to perform well during the autologous fat transfer procedure. As a result, multiple techniques have evolved that produce extremely varied results that are not scientifically verifiable. The objectives of this paper are to (1) review the events that are traumatic for the lipocyte and review how those events can be improved through new instrumentation; (2) review the use of the centrifuge and consider replacement of the centrifuge with an effective filter system; (3) establish instrument standards that will encourage scientific technique verification; and (4) introduce a standardized autologous fat transfer instrument that will save time, reduce significant trauma, and have standardized features to promote accurate scientific study.

Methods:

Information was obtained via a questionnaire, internet investigation, trade show information, personal discussions with surgeons, and the author's experience. Information from the questionnaire was used in the design of a new, improved standardized instrument.

Results:

During this study, an instrument was designed that would reduce operating room time considerably. Most of the time reduction was secondary to keeping the fat in the harvest syringe without transferring or centrifuging. This change in procedure would also considerably reduce lipocyte trauma in all 12 of the commonly accepted lipocyte trauma categories. In addition, the instrument could be standardized with multiple features that would give the surgeon confidence that the surgical results would not change because of the instruments.

Conclusions:

The Tissu-Trans™ device that was designed during this study significantly saves time, simplifies the procedure, and has standardized features that allow for scientific studies that are more accurate. The equipment offers simplicity and “feature latitude,” allowing the surgeon to perform all of the major steps (harvest, filter, irrigate, treatment, and reinjection) from a single harvest syringe. Although all 12 of the traumatic events for lipocytes were reduced in intensity, one should not leap to the conclusion that this correlates with increased lipocyte survival. To date, this has not been proven. Further clinical testing will be necessary to obtain this information.

Enhancement of Autologous Fat Transplantation with Platelet Rich Plasma

Introduction:

Adipose tissue is readily available for autotransplantation. Over many years, the popularity of fat transplantation surgery has waxed and waned as a result of relatively inconsistent and unpredictable survival. Many factors influence the success of autologous fat tissue grafts, some of which can be controlled by the surgeon. Examples include the use of minimally traumatic cannulae, low pressure suction, careful handling of graft tissues, and aseptic techniques. There is emerging evidence that fat grafts may be made more reliable and consistent by careful selection of donor sites and by influencing certain healing mechanisms that control cellular recruitment, migration, and differentiation at the recipient site.

Materials and Methods:

This paper presents an innovative technique that provides a means to isolate autologous platelet rich plasma for use with autologous fat for the purposes of enhanced tissue augmentation.

Results:

The apparent concentration and greater quantity of cellular grafts observed after utilization of these techniques seem to yield a higher proportion of graft volume retention.

Discussion:

This technique is intended to promote or accelerate the healing phase after grafting, enhance the intended augmentation retention volume, potentially reduce secondary calcifications and microcyst formation, and maximize the transplant unit volume by reducing the extracellular fluids transferred with the grafts.

Autologous fat grafting: current state of the art and critical review

BACKGROUND

Despite the widespread use of autologous fat grafting in both reconstructive and cosmetic surgery, volume retention remains a significant problem. We aimed to critically appraise the current body of literature in fat grafting to provide a framework to guide application and comparison.

METHOD

Search of scientific databases and gray literature was conducted. Articles examining nonadipogenic applications of adipose tissue and those specific to breast reconstruction were excluded.

RESULTS

One hundred three articles were included. These fell under the headings of donor site, effect of infiltration solution, harvest method, effect of centrifugation, reinjection method, supplementation, the role of adipose-derived stem cells, and scaffolding.

CONCLUSIONS

Despite the significant research effort in this field, there remains no consensus as to the optimum technique. This stems from the vast array of research methods and short follow-up durations. Further, extrapolation of in vitro results to clinical settings has led to many conflicting practices.

The discordant histology of grafted fat: a systematic review of the literature

BACKGROUND

All combinations of harvesting, processing, and injection have been attempted to maximize fat graft take following transplantation. Two theories behind fat transplantation have been proposed: cell survival and host replacement. Although the cell survival theory states that fat cells survive and undergo neovascularization following transfer, host replacement theory predicts adipocyte necrosis and replacement of cells by host tissues. Whether or not transferred fat survives, proliferates, or is replaced by fibrous tissue is relevant for the investment of future resources into this thriving field of research.

METHODS

A literature search of the MEDLINE and Cochrane databases was performed for studies focusing on the histology of grafted fat after transplantation up to December of 2013. Histologic examinations of grafted fat were reviewed and compared in humans and animals.

RESULTS

Sixty-six articles met inclusion criteria, and eight of them were human studies. There was widespread diversity in the method of fat harvest and transfer among the studies, and the date of examination after transfer. Many studies reported the presence of viable adipocytes, although an extensive amount of fibrosis and inflammatory infiltration was also seen, depending on the period of examination.

CONCLUSIONS

Free fat grafts show a variable response following transplantation, with significant disagreement in the reported evidence. Although neovascularization and preservation of adipocyte architecture appear possible, other fat grafts are completely replaced by necrotic ghost cells and fibrotic ingrowth. Adipocyte survival likely contributes to volume maintenance, but fibrosis may also play a role.

Fat grafting: a citation analysis of the seminal articles

Background:

There has been substantial rise in the volume of published works on fat transfer in the medical literature in the past 25 years, and this is indicative of its growing popularity. However, many unanswered questions remain, and there is no consensus as to the optimum technique. Consequently, the scientific and clinical research on fat grafting continues to increase rapidly. The purpose of our study was to perform a bibliometric analysis of the most-cited articles in fat transfer.

Methods:

Through the Web of Science, all articles relating to fat grafting were identified in the plastic and reconstructive literature. The 100 most-cited articles were identified and analyzed individually.

Results:

Total citations ranged from 35 to 363 and the most-cited paper by Sidney Coleman was published in Plastic and Reconstructive Surgery. The United States produced 46% of the most-cited papers, and the University of California was the most prolific institution. Twenty-one articles focused on lipofilling to the face while 14 articles looked at fat grafting to the breast.

Conclusions:

The scientific relevance of a published work is reflected in the number of citations from peers that it receives. Therefore, the 100 most-cited papers in fat grafting have been the most influential articles on this field, and they are likely to be the ones that are remembered most.

The fate of nonvascularized fat grafts: histological and bioluminescent study

Background:

Nonvascularized fat grafting has become one of the most popular options for breast contouring. However, the survival process of the grafts remains to be elucidated. In this study, we tracked the fate of nonvascularized fat grafts with in vivo bioluminescence and immunohistochemistry.

Methods:

Nonvascularized fat grafts or vascularized adiposal flaps from luciferase transgenic rats were transplanted to Lewis rats. The bioluminescent signals from the grafts were monitored longitudinally. In addition, nonvascularized fat grafts from Lewis rats were engrafted to Lewis rats and the viability of the adipocytes in the grafts was evaluated with immunohistochemical staining for perilipin at postoperative week 1, 2, 3, 4, and 6.

Results:

The bioluminescent signals from the nonvascularized fat grafts increased drastically from postoperative day 3 to 7, stayed flat from day 7 to 12, and declined from day 12 to 17, whereas those from the vascularized fat flaps remained throughout the entire postoperative period. Immunohistochemistry revealed that the survival zones with large adipocytes were decreased within 2 weeks and the regenerating zones with small adipocytes appeared after 3 weeks.

Conclusions:

Our study showed the process of survival and regeneration of nonvascularized fat grafts and suggested that graft-derived stromal cells proliferated within 7 days after transplantation and differentiated into adipocytes after postoperative week 3.

De novo adipogenesis for reconstructive surgery

Autografting of lost soft tissue is an important subject of the plastic and reconstructive surgery and autograft of fat pads has been only technique for this goal. However, the results are disappointing because of absorption of the grafts with time. Adipoblasts or adipocyte precursor cells distribute widely in connective tissues and they can proliferate and mature into adipocytes even in the adult body. In experiments using mice, we found that de novo adipogenesis of endogenous precursor cells can be induced by injecting reconstituted basement membrane, Matrigel, supplemented with more than 1 ng/ml of bFGF. This adipogenesis was reproducibly induced by subcutaneous injection over the chest, lateral abdomen or head. Adipogenesis was induced even in ear cartilage or in muscle. To evaluate the possibility of future application of this de novo adipogenesis to plastic and reconstructive surgery, we have reviewed updated knowledge of the adipogenesis.

Increased survival of free fat grafts and vascularization in rats with local delivery of fragmin/protamine microparticles containing FGF-2 (F/P MP-F)

We evaluated the effects of fragmin/protamine micro-particles (F/P MPs) containing FGF-2 (F/P MP-F) as carriers for the controlled release of FGF-2 for adipocyte-survival and capillary formation in inbred rats with subdivided free fat grafts. F/P MPs could immobilize FGF-2, thereafter gradually releasing the bound FGF-2. Inbred Fisher 344 rats weighing around 150 g were anesthetized and implanted with paste comprising harvested fat combined with F/P MP-F. The effect of F/P MP-F on the survival, granulation, and capillary formation in fat grafts was histologically compared with control grafts containing either FGF-2, F/P MPs or PBS. The control fat grafts became attached to tissues adjacent to the implantation site and were significantly resorbed after 30 days. In contrast, pink, soft, supple grafts were compressible and were little resorbed in the group given F/P FP MP-F at 30-120 days. Normal adipocytes were obviously decreased in the control groups with increased granulation tissues, whereas normal adipocytes with capillary formations were maintained in the F/P MP-F group. Thus, adding F/P MP-F to subdivided fat grafts helps to improve graft volume retention and survival in soft-tissue reconstruction through accelerating adipocyte-survival rates and angiogenesis.

Cryopreservation of autologous fat grafts harvested with the Coleman technique

The viability of fat grafts harvested with an established technique after cryopreservation remains unknown. This study was conducted in vitro to evaluate the viability of autologous fat grafts harvested with the Coleman technique and subsequently preserved with our preferred cryopreservation method. Eight adult females were enrolled in this study. In each patient, 10 mL of fat grafts were harvested with the Coleman technique by a single surgeon from the lower abdomen. In group 1, 5 mL of fresh fat grafts were mixed with cryoprotective agents and underwent cryopreservation with controlled slow cooling and fast rewarming. In group 2, 5 mL of fresh fat grafts without cryopreservation from the same patient served as a control. The fat graft samples from both groups were evaluated with trypan blue vital staining, glycerol-3-phophatase dehydrogenase assay, and routine histology. Viable adipocyte counts were found similar in both group 1 and group 2 (3.46 +/- 0.91 vs. 4.12 +/- 1.11 x 10/mL, P = 0.22). However, glycerol-3-phophatase dehydrogenase activity was significantly lower in group 1 compared with group 2 (0.47 +/- 0.09 vs. 0.66 +/- 0.09 u/mL, P < 0.001). Histologically, the normal structure of fragmented fatty tissues was found primarily in both groups. Our results indicate that autologous fat grafts harvested with the Coleman technique and preserved with our preferred cryopreservation method have a normal histology with near the same number of viable adipocytes as compared with the fresh fat grafts. However, those cryopreserved fat grafts appear to have a less optimal level of adipocyte specific enzyme activity compared with the fresh ones and thus may not survive well after they are transplanted without being optimized.

Effect of autologous platelet adhesives on dermal fat graft resorption following reconstruction of a superficial parotidectomy defect: a double-blinded prospective trial

BACKGROUND

Dermal fat grafts are used to reconstruct facial contour defects but may undergo variable resorption. Application of autologous platelet adhesive may improve outcomes. The primary objective was to compare resorption of dermal fat grafts for parotidectomy defects, between patients receiving autologous platelet adhesive versus controls.

METHODS

This was a double-blinded prospective cohort at a tertiary care center. Volumetric analyses of dermal fat graft measured by MRI scans. Resorption was determined by comparing 1- and 6-month MRIs in each patient. Complications, Frey's Syndrome, and patient satisfaction were also assessed.

RESULTS

Twelve patients completed the study. A significant reduction in graft resorption was seen in the treatment group (57% vs. 31%, p = .01). Three patients in the control group developed fat liquefaction. Patient perceived significant differences in scar and contour.

CONCLUSION

Application of autologous platelet adhesives improved graft viability and patient satisfaction at 6 months.

Autologous fat grafts harvested and refined by the Coleman technique: a comparative study

BACKGROUND

The viability of fat grafts obtained by even a well-established technique remains poorly studied and unknown. This study was designed to determine the viability of fat grafts harvested and refined by the Coleman technique.

METHODS

Sixteen adult white women were enrolled in this study. In group 1 (n = 8), fat grafts were harvested and processed with the Coleman technique by a single surgeon from the abdomen of each patient according to his standardized method. In group 2 (n = 8), fat grafts were harvested with the conventional liposuction by another surgeon. After centrifugation, the resulting middle layer of tissue was collected. All fat graft samples were analyzed for the following studies: trypan blue vital staining for viable adipocyte counts, glycerol-3-phophatase dehydrogenase assay, and routine histologic examination.

RESULTS

The higher viable adipocyte counts were found in group 1 compared with group 2 (4.11 +/- 1.11 versus 2.57 +/- 0.56 x 10 cells/ml; p < 0.004). The level of glycerol-3-phophatase dehydrogenase activity was significantly higher in group 1 compared with group 2 (0.66 +/- 0.09 versus 0.34 +/- 0.13 U/ml; p < 0.0001). Histologic examination showed normal structure of fragmented fatty tissues in both groups.

CONCLUSIONS

Although fat grafts obtained by both methods maintain normal histologic structure, the Coleman technique yields a greater number of viable adipocytes and sustains a more optimal level of cellular function within fat grafts and should be considered superior to conventional liposuction as a preferred method of choice for fat graft harvesting.

Preliminary Survival Studies on Autologous Cultured Skin Fibroblasts Transplantation by Injection

In the correction of aesthetic impairments on the face, dermal, and superficial subcutaneous defects, adequately safe implant material is required. Cultured autologous skin fibroblasts, as a protein repair system, create a living injectable system that has been utilized effectively to treat rhytids, depressed scars, subcutaneous atrophy, acne irregularities, and laser wounds. To evaluate the new method, we have investigated the survival and collagen secretion of autologous transplanted fibroblasts. In this study, rabbit fibroblasts were cultured and expanded. Cells (8 × 107/ml) were injected into the superficial and deep dermal junction of the dorsal ears. Two rabbits were injected independently with labeled [3H]TdR fibroblasts; similarly, eight rabbits were given unlabeled transplanted cells in the right ear and vehicle in the left. Each site was injected three times with the same amount of cells every 2 weeks. The grafts were evaluated for 5 months. After explantation, the samples were collected from the injected sites and stained with autoradiography, H&E, and sirius red, respectively. According to the histological observations, the [3H]TdR-labeled cells survived and large amounts of embryo fibroblasts were found in the experimental subgroup of the labeled cell group. The depth of dermis was significantly different between the experimental subgroup (701.3 ± 31.5 μm) and the control subgroup (638.3 ± 23.9 μm) of the unlabeled group (p < 0.01). There was also a significant difference of collagen III between the experimental subgroup (2.63 ± 1.41 cm2) and the control subgroup (1.05 ± 0.90 cm2) (p < 0.05). There was no significant difference of collagen I between the experimental subgroup (56.25 ± 14.41 cm2) and the control subgroup (55.41 ± 16.59 cm2) (p > 0.05). The results obtained demonstrate that the distinction of the depth of dermis should be interpreted by the increase of collagen III, instead of collagen I, which is produced by the transplanted fibroblasts. The investigation indicated that transplanted autologous skin fibroblasts could provide a potential and effective approach to treat minor facial tissue deficiencies.

Effect of local, long-term delivery of platelet-derived growth factor (PDGF) on injected fat graft survival in severe combined immunodeficient (SCID) mice

SUMMARY BACKGROUND

Autogenous fat injection is widely used for the correction of acquired and congenital soft tissue defects. However, the high absorption rate results in the need for over-correction of the defect and repeat procedures. We hypothesised that platelet-derived growth factor (PDGF), a potent mitogen and known stimulant for murine preadipocytes, would improve fat graft survival when concentrations were sustained with a gelatine microsphere delivery system.

METHODS

Abdominal fat was harvested from an otherwise healthy 43-year-old woman during a breast reconstruction. Prior to subdermal injection into severe combined immunodeficient (SCID) mice, the fat grafts were divided into 1-ml aliquots, mixed with microspheres bound to PDGF, free PDGF, or nothing depending on its experimental group, and weighed. The following experimental groups were thus created (minimum n=8 per group): (1) fat graft control, (2) fat graft with free PDGF, (3) fat graft with blank microspheres, and (4) fat graft with microspheres bound to PDGF. After 12 weeks, the fat xenografts were harvested for analysis of weight maintenance and histological and morphometric evaluation.

RESULTS

The addition of PDGF bound to gelatine microspheres was effective in improving xenograft weight maintenance (P=0.018) and preservation of adipose tissue architecture (P<0.0005) compared to controls at 3 months. The microspheres were completely absorbed at 12 weeks.

CONCLUSIONS

Sustained, local delivery of PDGF via a gelatine microsphere delivery system resulted in improved weight maintenance of the xenografts with greater preservation of adipose tissue architecture at 3 months compared to controls.

Introduction of an easy technique for purification and injection of autogenous free fat parcels in correcting of facial contour deformities

BACKGROUND

Facial contour deformities usually result from congenital abnormalities, trauma, and the aging process. All depressions in the face, including glabella wrinkles and mild retrogression of chins, fall in this category. Local injection of autogenous fat parcels has been introduced for correction of these facial deformities for almost 20 years.

METHOD

Using common materials (gauzes and cotton sticks), a simple technique was used by us to purify syringe-suctioned fat parcels followed by a multilayered injection of the purified fat tissue into implantation sites to treat the facial contour deformities in 152 sites of 50 cases with successful outcomes.

RESULTS

Thirty-nine sites in 17 cases were followed up from 13 months to 37 months (average, 22.8 months). The injected fat parcels deposited successfully and the increasing volume maintained well. The impact factors on the successful deposit of the injected fat parcels included the extent of mechanical injuries to the fat cells during liposuction and lipoinjection, application of the purification procedure, and postsurgery immobilization as well as the blood-nourishing situation of recipient sites. Postoperative complications included undercorrection, overcorrection, small fat mass, unevenness, or irregularity.

CONCLUSION

The introduced purification and injection techniques provided a comparative simple and reliable method in facial recontouring treatment. The local volume could be increased successfully by means of controlling the influencing factors of fat parcel deposit.

An Alternative Method for Harvest and Processing Fat Grafts: An In Vitro Study of Cell Viability and Survival

BACKGROUND

Adipocyte viability has been emphasized as essential for fat graft survival. There is no universal agreement on the methodology for handling fat grafts.

OBJECTIVE

Two different methods of fat harvesting and techniques of tissue processing were compared by assessing cell viability, damage, and growth in vitro.

METHOD

Fat was harvested from Zucker rats (n = 5) using (1) a 3-mm liposuction cannula with a 60-cc syringe (right side) or (2) a 2-mm blunt needle with a 10-cc syringe adapted to a fine-needle aspiration apparatus (left side). Tissues were then processed by decantation or cotton towel drying. Five samples for each of the four techniques were studied. Fat samples were processed for culture, and adipocytes and preadipocytes were plated in culture medium and expanded in vitro. Cell viability was assessed using cell counts, the MTT proliferation assay, G3PDH activity, and Oil Red O stain.

RESULTS

Method 1 exerted significantly higher pressure (p = 0.009) than method 2 (643 +/- 2.5 versus 537 +/- 13.6 mm Hg). A larger oil layer was apparent with method 1 (1.11 +/- 0.29 g) than with method 2 (0.56 +/- 0.28 g). In addition, the highest number of viable preadipocytes was obtained using method 2B (p = 0.017). In culture, preadipocytes plated in 4F differentiation medium started to differentiate after 1 week, while those in Dulbecco's modified Eagle's medium/F12 with serum proliferated but did not differentiate. Mature adipocytes in adipogenic medium dedifferentiated and later redifferentiated into fat cells.

CONCLUSIONS

Fat viability was better when fat was harvested by fine-needle aspiration. The plasticity of mature adipocytes and preadipocytes in vitro suggested that both might be involved in fat graft integration.

Principles of liposuction

There has been a dramatic increase in liposuction procedures during the last decade by both dermatologic and plastic surgeons. It is one of the most commonly performed cosmetic surgery procedures. Since its inception in 1976, numerous major advances have made the procedure more successful for both the surgeon and patient alike. This article reviews the current principles of liposuction and serves as a comprehensive overview of recent innovations in this field.

Autologous Human Fat Grafting: Effect of Harvesting and Preparation Techniques on Adipocyte Graft Survival

BACKGROUND

Autogenous fat transfer with lipoinjection for soft-tissue augmentation is a commonly used technique without a universally accepted approach. The high percentage and variable amount of fat resorption reduce the clinical efficacy of this procedure and often result in the need for further grafting. The purposes of this study were to evaluate the effect of different harvesting and preparation techniques on human fat tissue viability and to determine fat tissue viability rates among the different fat preparations transplanted into a severe combined immune deficiency mouse model at 3 months.

METHODS

Using standard liposuction and syringe aspiration, fat was removed from patients (n = 3) undergoing elective body contouring. Tissue was prepared by six different combinations of centrifugation and/or washing the cells with lactated Ringer's solution or normal saline. Metabolic activities of fat cell viability were monitored to assess overall cell viability. To analyze viability over 3 months, freshly harvested tissue specimens (minimum n = 5) were prepared by a combination of various procedures (wash, centrifugation, and different solutions) and subsequently injected under the dorsal flank skin of severe combined immune deficiency mice in two experiments. Mice were monitored for 12 weeks and the fat xenografts were removed for mass and histological evaluations.

RESULTS

Metabolic analyses showed improved cell viability in tissue specimens undergoing minimal manipulation. No significant differences in fat cell viability, as assessed by graft weight maintenance or histologic evaluations, were observed with regard to harvesting or preparation techniques.

CONCLUSIONS

Improved viability of freshly harvested but untreated fat specimens may be expected as compared with grafts that have undergone additional manipulations. No unique combination of preparation or harvesting techniques appeared to be more advantageous on transplanted fat grafts at 3 months. This study also demonstrated a reliable animal model for future investigation into examining novel applications for augmenting fat graft survival.

Fat Injection: A 20-Year Revision

In the last 20 years, several different techniques of lipoinjection have been developed. Nevertheless, a standard procedure has not been adopted by all practitioners. There is no agreement as to the best way of processing the fat to ensure maximal take and viability of the graft. Other controversial issues include the ideal cannula for harvesting and reinjection, the presence of blood in the transplanted fat, trauma, air exposure, contamination of the graft, durability, and fat cell survival. Newly emerging approaches to fat tissue engineering with the use of cultured autologous preadipocytes may improve the technique of fat injection and transplant.

The effect of interleukin-8 on the viability of injected adipose tissue in nude mice

Adipose tissue injection as a free graft for the correction of soft-tissue defects is a widespread procedure in plastic surgery. The main problem in achieving long-term soft-tissue augmentation is partial absorption of the injected fat and hence the need for overcorrection and re-injection. The purpose of this study was to improve the viability of the injected fat by the use of interleukin-8. The rationale for the use of interleukin-8 was its abilities to accelerate angiogenesis and attract inflammatory cells and fibroblasts, providing the injected adipocytes more feeding vessels and a well-established graft bed to enhance their viability. Human adipose tissue, obtained by suction-assisted lipectomy, was re-injected into the subcutis in the scalp of nude mice. Interleukin-8 (0.25 ng) was injected subcutaneously to the scalp as a preparation of the recipient site 24 hours before the fat injection and was added to the fat graft itself (25 ng per 1 cc of injected fat). In the control group, pure fat without interleukin-8 was injected and no interleukin-8 was added for the preparation of the recipient site. One cubic centimeter of fat was injected in each animal in both the study and control groups. There were 10 animals in each group. The animals were euthanized 15 weeks after the procedure. Graft weight and volume were measured and histologic evaluation was performed. In addition, triglyceride content and adipose cell sizes were measured as parameters for fat cells viability. Histologic analysis demonstrated significantly less cyst formation in the group treated with interleukin-8. No significant differences were found between the groups with regard to graft weight and volume or the other histologic parameters investigated. No significant differences were demonstrated in adipose cell sizes and their triglyceride content. In conclusion, less cyst formation, indicating improved quality of the injected fat, can be obtained by the addition of interleukin-8. Further studies of various dosages of interleukin-8 and their long-term effect are required before these encouraging results could be applied clinically.

De novo adipose formation in a vascularized engineered construct

While the field of tissue engineering is a burgeoning one, progress with fat engineering has lagged, due in large part to problems associated with nurturing and sustaining this unique tissue in vivo. In a pilot study using an experimental rat model, we induced liponeogenesis with a combination of Matrigel and basic fibroblast growth factor in an fibrovascular scaffold, isolating the construct to a pedicled blood supply (the superficial inferior epigastric vessels) via a silicone housing, creating an engineered three-dimensional adipose tissue construct. Adipose tissue and vascular ingrowth were assessed histologically and followed by serial study at 4-week intervals for 16 weeks. We demonstrated persistence of shaped adipose tissue constructs over time, and postulate that incorporating a vascular supply may enhance the durability of experimentally induced fat constructs and potentially provide a means for microsurgical transfer of the construct.

Photocured, Styrenated Gelatin-Based Microspheres for de Novo Adipogenesis through Corelease of Basic Fibroblast Growth Factor, Insulin, and Insulin-Like Growth Factor I

De novo adipose tissue formation appears to proceed via two different biological events: neovascularization and spontaneous accumulation of preadipocytes and subsequent differentiation to mature adipocytes. In this article, we perform accelerated de novo adipose tissue engineering using photocured, styrenated, gelatin-based microspheres (SGMs) with different drug release rates of immobilized angiogenic and adipogenic factors. The concept of this system is to induce neovascularization and migration of endogenous preadipocytes by the rapid delivery of the angiogenic factor basic fibroblast growth factor (bFGF), followed by the proliferation and differentiation of preadipocytes into adipocytes by the prolonged delivery of the adipogenic factors, insulin and insulin-like growth factor I (IGF-I). Bioactive substance-immobilized SGMs with different drug release rates were prepared with different gelatin concentrations. An in vitro study showed the prolonged release of an immobilized model protein and the dependence of drug release rate on gelatin concentration. After the subcutaneous injections of SGMs immobilized with these bioactive substances in different combinations, the formation of masses or clusters of adipocytes was observed in rats. Triglyceride content in the injection site for the group that received bFGF-, insulin-, and IGF-I-immobilized SGMs was significantly higher than that for the group that received insulin- and IGF-I-immobilized SGMs 4 weeks after the injection of microspheres. These results suggest that the system developed here is effective for the de novo formation of adipose tissue as it enables the induction of the two-step biological reaction by single injection.

Orthogonal polarization spectral imaging versus intravital fluorescent microscopy for microvascular studies in wounds

The aim of this study was to validate orthogonal polarization spectral (OPS) imaging against intravital fluorescence microscopy (IFM) for microvascular measurements in normal skin and during wound healing. Experiments were performed on the ears of hairless mice (N = 8). The diameter of arterioles and venules, red blood cell velocity in venules, and the functional capillary density were assessed under normal conditions using OPS imaging and IFM. After creation of a circular wound, these observations were repeated at the identical microvascular regions on days 4, 7, 10, and 15. Images were videotaped, and CapImage was used for off-line computer-assisted analysis. Using OPS imaging, the microcirculation of wounded skin in hairless mice could be observed successfully. The regression analyses against standard IFM revealed a significant (p < 0.001) correlation for measurements of all microcirculatory parameters investigated (venular diameter: r(2) = 0.98, N = 345; red blood cell velocity: r(2) = 0.51, N = 326; functional capillary density: r(2) = 0.44, N = 156). However, for diameter as well as for functional capillary density measurements, OPS imaging yielded lower absolute values compared with IFM. The authors were able to validate OPS imaging against IFM for the measurement of microvascular parameters in an animal model of skin wound healing. Such a device should now help to study the role of microcirculation in physiology and pathophysiology during wound healing in patients. First clinical investigations are promising.

Fat transfer techniques: the effect of harvest and transfer methods on adipocyte viability and review of the literature

BACKGROUND

Autologous fat transplantation is an excellent tool for filling defects and augmenting tissue. The literature provides a variety of reports with varying degrees of success or failure. The procedure is operator dependent and relies on the techniques of harvesting, cleansing, and reinjection.

OBJECTIVE

To evaluate various retrieval and reinjection techniques to see their effect on the viability of the fat cells.

METHODS

Fat was removed from five patients utilizing various cannulas, needles, suction pressures, and centrifugation for collection and reinjection. Preoperative external ultrasound and massage were evaluated as well as the use of the ratchet gun for injection. The fat was routinely cleansed of blood and tumescent solution products by means of washing with normal saline and then decanting repeatedly until the infranatant solution was clear.

RESULTS

Histologic examination of the fat cells showed the central core of fat and edges of the core had 98-100% intact cells (presumably viable) in every specimen except when -700 mmHg vacuum was used for fat collection where cell damage was greater than 10% and when preoperative massage was performed where cell damage was 30%. Preoperative external ultrasound did not appear to damage the fat cell but did disrupt some of the fibrous tissue holding the fat cells in large bundles.

CONCLUSION

The variety of techniques used to collect, clean, and reinject fat do not damage the fat cells except for the collection of fat at -700 mmHg vacuum. External ultrasound, preoperatively, does not destroy fat cells but produces smaller bundles of fat. The ratchet gun does not result in increased fat cell loss. Preoperative massage causes 30% cell loss and deformation of 80% of the remaining cells.

Human preadipocytes seeded on freeze-dried collagen scaffolds investigated in vitro and in vivo

Currently, there is no adequate implant material for the correction of soft tissue defects such as after extensive deep burns, after tumor resection and in hereditary and congenital defects (e.g. Romberg's disease, Poland syndrome). The autologous transplantation of mature adipose tissue has poor results. In this study human preadipocytes of young adults were isolated and cultured. 10(6) preadipocytes were seeded onto collagen sponges with uniform 40 microm pore size and regular lamellar structure and implanted into immunodeficient mice. Collagen sponges without preadipocytes were used in the controls. Macroscopical impression, weight, thickness, histology, immunohistochemistry (scaffold structure, cellularity, penetration depth of the seeded cells) and ultrastructure were assessed after 24 h in vitro and after explantation at 3 and 8 weeks. Preadipocytes penetrated the scaffolds 24 h after seeding at a depth of 299+/-55 microm before implantation. Macroscopically after 3 and 8 weeks in vivo layers of adipose tissue accompanied by new vessels were found on all preadipocyte/collagen grafts. The control grafts appeared unchanged without vessel ingrowth. There was a significant weight loss of all grafts between 24 h in vitro and 3 weeks in vivo (p < 0.05), whereas there was only a slight weight reduction from week 3 to 8. The thickness decreased in the first 3 weeks (p < 0.05) in all grafts. The preadipocyte/collagen grafts were thinner but had a higher weight than the controls at this point in time. The histology showed adipose tissue and a rich vascularisation adherent to the scaffolds under a capsule. The control sponges contained only few cells and a capsule but no adipose tissue. Human-vimentin positive cells were found in all preadipocyte/collagen grafts but not in the controls, penetrating 1188+/-498 microm (3 weeks) and 1433+/-685 microm (8 weeks). Ultrastructural analysis showed complete in vivo differentiation of viable adipocytes in the sponge seeded with preadipocytes. Formation of extracellular matrix was more pronounced in the preadipocyte/collagen grafts. The transplantation of isolated and cultured preadipocytes within a standardised collagen matrix resulted in well-vascularised adipose-like tissue. It is assumed that a pore size greater than 40 microm is required, as preadipocytes enlarge during differentiation due to incorporation of lipids.

The effect of hyperbaric oxygenation on the viability of human fat injected into nude mice

Autologous free-fat injection for the correction of soft-tissue defects has become a common procedure in plastic surgery. The main shortcoming of this method for achieving permanent soft-tissue augmentation is the partial absorption of the injected fat, an occurrence that leads to the need for both overcorrection and repeated fat reinjection. Improving the oxygenation of the injected fat has been suggested as a means of helping to overcome the initial critical phase that occurs postinjection (when the fat cells are nourished by osmosis), increasing phagocyte activity, accelerating fibroblast activity and collagen formation, and enhancing angiogenesis. In addition, the hyperbaric oxygen-mediated decrement in endothelial leukocyte adhesion will decrease cytokine release, thereby reducing edema and inflammatory responses. The purpose of the present study was to examine the effect of hyperbaric oxygenation on improving the viability of injected fat. Adipose tissue obtained from human breasts by suction-assisted lipectomy was injected into the subcuticular nuchal region in nude mice. The mice were then exposed to daily hyperbaric oxygen treatments, breathing 100% oxygen at 2 atmospheres absolute (ATA) for 90 minutes. The duration of the administered hyperbaric oxygen therapy was 5, 10, or 15 days, according to the study group. Mice exposed to normobaric air alone served as the control group, and each group included 10 animals. The rats were killed 15 weeks after fat injection. The grafts were dissected out, weight and volume were measured, and histologic evaluation was performed. In all of the study groups, at least part of the injected fat survived, giving the desired clinical outcome. No significant differences could be found between the groups regarding fat weight and volume. Histopathologic examination of the dissected grafts demonstrated a significantly better integrity of the fat tissue in the group that received hyperbaric oxygen for 5 days (p = 0.047). This finding was manifested by the presence of well-organized, intact fat cells, along with a normal appearance of the fibrous septa and blood vessels. The worst results were found in animals treated by hyperbaric oxygenation for 15 consecutive days. An inverse correlation was found between an increased dose of the high-pressure oxygen and fat tissue integrity (r = -0.87, p = 0.076). The toxic effects of highly reactive oxygen species on fat cells might explain the failure of an excessively high dose of hyperbaric oxygen to provide any beneficial outcome. The clinical relevance of these results should be further investigated.