Nonsurgical breast enlargement using an external soft-tissue expansion system

Preconditioning strategies for improving the outcome of fat grafting

Autologous fat grafting is a common procedure in plastic, reconstructive and esthetic surgery. However, it is frequently associated with an unpredictable resorption rate of the graft depending on the engraftment kinetics. This, in turn, is determined by the interaction of the grafted adipose tissue with the tissue at the recipient site. Accordingly, preconditioning strategies have been developed following the principle of exposing these tissues in the pre-transplantation phase to stimuli inducing endogenous protective and regenerative cellular adaptations, such as the up-regulation of stress-response genes or the release of cytokines and growth factors. As summarized in the present review, these stimuli include hypoxia, dietary restriction, local mechanical stress, heat and exposure to fractional carbon dioxide laser. Preclinical studies show that they promote cell viability, adipogenesis and angiogenesis, while reducing inflammation, fibrosis and cyst formation, resulting in a higher survival rate and quality of fat grafts in different experimental settings. Hence, preconditioning represents a promising approach to improve the outcome of fat grafting in future clinical practice. For this purpose, it is necessary to establish standardized preconditioning protocols for specific clinical applications that are efficient, safe and easy to implement into routine procedures.

Mechanism of Origin of Positive Tissue Pressure During Negative-Pressure Wound Therapy

This report provides a simplified insight into the previously unexplained physical mechanism of the origin of local positive tissue pressure during negative-pressure wound therapy (NPWT). A chain of 2 spring model could be used to show the biomechanical interaction between the NPWT dressing and the adjacent body tissues. It is important to assume that the application of NPWT dressing to the body surface creates a new closed compartmentalized volume. Air suction generates local positive pressure within the dressing due to unopposed atmospheric load, which in turn leads to compression of the adjacent tissues and induction of positive pressure there. Analysis of the biomechanical events during NPWT implies the possibility of tissue injury by positive pressure and suggests clinical alertness in regard to the balance between the size of the NPWT dressing and suction pressure as well as further related research.

A Novel Approach for Tuberous Breast Correction Using Power-Assisted Liposuction, Loops, and Lipofilling (PALLL)

BACKGROUND

Autologous fat grafting has recently gained popularity in breast and reconstructive procedures.

OBJECTIVES

The aim of this paper was to describe a tricomposite tuberous breast reconstruction that comprises matrix dissociation through extensive tunnelization, tissue recruitment with loops, and autologous fat transfer. This approach, called "matrix modeling," was implemented by the power-assisted liposuction, loops, and lipofilling (PALLL) technique as a method to expand the lower pole, reshape the breast, and increase breast volume.

METHODS

Between 2014 and 2020, a total of 47 patients underwent tuberous breast correction by combined lipofilling and the use of breast loops. The patient population included patients with unilateral or bilateral tuberous breasts of any stage. Patients who were active smokers, lean, or who desired large breasts were excluded from the study.

RESULTS

Of the 47 patients (mean age, 26 years), 31 had bilateral malformations. The mean recruited flap volume was 212 mL. A single session (mean transfer volume, 163 mL) was required in 34 cases (72%). A second session (mean transfer volume, 182 mL) was necessary in the remaining 28% of cases. Patients were very satisfied in 93% of cases and satisfied in 7% of cases. One infection was observed. The mean operative time was 67 minutes. Imaging performed preoperatively and 1 year postoperatively did not reveal any anomalies other than oil cysts (4%).

CONCLUSIONS

Tricomposite breast reconstruction by PALLL is a novel, simple, safe, and alternative technique for tuberous breast correction by remodeling the matrix. The aesthetic outcome is natural, implant free, and long lasting.

LEVEL OF EVIDENCE: 4

Augmentation Mammoplasty With External Volume Expander-Assisted Autologous Fat Grafting in 305 Asian Patients

BACKGROUND

External volume expander (EVE)-assisted autologous fat grafting is suitable for breast augmentation, but no large sample study in Asia has confirmed this method.

OBJECTIVES

The authors reported their experience and outcomes in augmentation mammoplasty with EVE-assisted autologous fat grafting.

METHODS

A retrospective study was conducted in 305 female patients who underwent augmentation mammoplasty with EVE-assisted fat grafting between September 2012 and December 2020. Doctors utilized Crisalix (Crisalix S.A., Lausanne, Switzerland) for 3-dimensional (3D) imaging acquisition to measure the increase in breast volume to evaluate doctor satisfaction. The Preoperative Satisfaction with Breast and BREAST-Q questionnaires were employed to assess patients' preoperative and postoperative satisfaction, respectively.

RESULTS

The 305 female patients were aged 18 to 50 years (mean, 35.9 years). Among them, 68.52% were "very satisfied," 18.69% were "somewhat satisfied," 11.15% were "somewhat dissatisfied," and 1.64% were "very dissatisfied" based on BREAST-Q analysis, whereas 100% were dissatisfied according to the Preoperative Satisfaction with Breast questionnaire. Doctors employed Crisalix to measure the increase in breast volume to evaluate doctor satisfaction. The results showed 76.01% had an increase in breast volume of 150 to 250 mL or >250 mL and were "satisfied" and "very satisfied," respectively, 21.64% had an increase of 50 to 149 mL and were "somewhat satisfied," and 2.30% had an increase <50 mL and were "dissatisfied." There were no complications, such as obvious fat liquefaction, infection, or fat embolism.

CONCLUSIONS

Augmentation mammoplasty with EVE-assisted fat grafting is effective and satisfying in China. Crisalix for 3D imaging acquisition is convenient and effective in measuring breast volume.

LEVEL OF EVIDENCE: 4

Promotion of dermal tissue engineering in a rat model using a composite 3D-printed scaffold with electrospun nanofibers and recipient-site preconditioning with an external volume expansion device

We hypothesized that use of a composite three-dimensionally (3D) printed scaffold with electrospun nanofibers in conjunction with recipient-site preconditioning with an external volume expansion (EVE) device would enable successful dermal tissue regeneration of a synthetic polymer scaffold. Cell viability, cell infiltration, extracellular matrix deposition, scaffold contraction, and mRNA expression by dermal fibroblasts cultured on three different scaffolds, namely, 3D-printed scaffold with a collagen coating, 3D-printed scaffold with an electrospun polycaprolactone nanofiber and collagen coating, and 3D-printed scaffold with an electrospun polycaprolactone/collagen nanofiber, were measured. Before scaffold implantation, rats were treated for 2 h with an EVE device to evaluate the effect of this device on the recipient site. Cell proliferation rates were significantly higher on the 3D-printed scaffold with electrospun polycaprolactone nanofiber and collagen coating than on the other scaffolds. In cell invasion studies, the 3D-printed scaffold with electrospun polycaprolactone nanofiber and collagen coating showed better cell integration than the other scaffolds. Under stereomicroscopy, fibroblasts adhered tightly to the electrospun area, and the fibroblasts effectively produced both collagen and elastin. Rat skin treated with an EVE device exhibited increased HIF-1α protein expression and capillary neoformation compared with control skin. Invasion of CD8⁺ cytotoxic lymphocytes surrounding the scaffold decreased when the recipient site was preconditioned with the EVE device. The composite 3D printed scaffold with electrospun nanofibers provided a favorable environment for proliferation, migration, and extracellular matrix synthesis by fibroblasts. Recipient-site preconditioning with an EVE device allowed for scaffold incorporation with less inflammation due to improved angiogenesis.

[Research progress of external volume expansion assisted autologous fat grafting for breast reconstruction]

OBJECTIVE

To review the application progress, mechanism, application points, limitations, and oncological safety of external volume expansion (EVE) assisted autologous fat grafting for breast reconstruction and provide a reference for optimizing the design of EVE.

METHODS

Based on the latest relevant articles, the basic experiments and clinical applications of EVE were summarized.

RESULTS

EVE can reduce interstitial fluid pressure, increase blood supply, and promote adipogenic differentiation, thereby benefiting the survival of transplanted fat. EVE assisted autologous fat grafting in clinical practice can improve the retention rate of breast volume and the outcome of breast reconstruction, meanwhile it doesn't increase the risk of local recurrence. But there is no standard parameters for application, and there are many complications and limitations.

CONCLUSION

EVE improves the survival of transplanted fat, but its complications and poor compliance are obvious, so it is urgent to further investigate customized products for breast reconstruction after breast cancer and establish relevant application guidelines.

Efficacy of breast augmentation using an external breast tissue expander for a shorter period while applying higher pressure: a preliminary study

Background Various types of external breast tissue expanders have been found to be effective for aesthetic breast augmentation. However, their use has been limited when compared with implant-based breast augmentation due to the burdensome nature of their application. This article reports the possibility that external breast tissue expanders may be applied safely and effectively with higher pressure and shorter application time.Methods The participants comprised patients who desired breast augmentation using the EVERA-RAPHA device between January 2020 and March 2020. A double-blinded prospective study was conducted on two groups of eight patients each, with either 60 mmHg or 100 mmHg of pressure applied. Standardized photographs were taken and blinded measurements of volume and circumference were made. The Mann-Whitney and paired t-tests were conducted.Results Sixteen patients were evaluated after 1 month of treatment. The women in groups 1 and 2 (60 mmHg and 100 mmHg, respectively) used EVERA-RAPHA for 15.400± 0.704 and 15.300±0.477 minutes per day, respectively. The mean volume increases in groups 1 and 2 were 39.000±42.526 cc and 27.700±20.260 cc, respectively. No patients dropped out of the study. All patients reported that the device was tolerable. Mild bruising was found in 62.5% of the patients in group 2.Conclusions Breast augmentation using external tissue expanders can be a safe, effective, and practical option. Pressures of 60 mmHg or 100 mmHg can be safely applied for a shorter duration. Larger studies are needed to further confirm our findings.

Recent Developments in Extracellular Matrix Remodeling for Fat Grafting

Remodeling of the extracellular matrix (ECM), which provides structural and biochemical support for surrounding cells, is vital for adipose tissue regeneration after autologous fat grafting. Rapid and high-quality ECM remodeling can improve the retention rate after fat grafting by promoting neovascularization, regulating stem cells differentiation, and suppressing chronic inflammation. The degradation and deposition of ECM are regulated by various factors, including hypoxia, blood supply, inflammation, and stem cells. By contrast, ECM remodeling alters these regulatory factors, resulting in a dynamic relationship between them. Although researchers have attempted to identify the cellular sources of factors associated with tissue regeneration and regulation of the microenvironment, the factors and mechanisms that affect adipose tissue ECM remodeling remain incompletely understood. This review describes the process of adipose ECM remodeling after grafting and summarizes the factors that affect ECM reconstruction. Also, this review provides an overview of the clinical methods to avoid poor ECM remodeling. These findings may provide new ideas for improving the retention of adipose tissue after fat transplantation.

Efficacy and Safety of External Volume Expansion (EVE) on Fat Grafting: A Systematic Review and Single-Arm Meta-Analysis

BACKGROUND

The autologous fat grafting is commonly used for reconstructive or aesthetic purposes. However, due to the huge variation in methods, its retention rate varies a lot. External volume expansion (EVE) has been used to treat recipient sites of fat grafting. Concerns have been raised regarding its efficacy and safety.

METHODS

We have searched PubMed, EMBASE, and the Cochrane Library for studies on EVE-assisted fat grafting published from 2000 to 2020. A meta-analysis was conducted to pool the retention rate. The incidence of complications was assessed for reconstructive or aesthetic purposes.

RESULTS

The 11 included studies involved 1152 patients with operations on 1794 breasts. Four studies were included in the meta-analysis. The pooled retention rate was 65% [95%CI 49, 79]. Eight studies reported the complications. The total complication incidence was 34%, which is 35% for the aesthetic group and 33% for the reconstructive group. The complication rate was not obviously different between the two groups.

CONCLUSIONS

The study shows that the EVE-assisted fat grafting has better retention rate than traditional fat grafting. However, the data showed that the complication rate was much higher in the EVE-assisted group.

Negative Pressure From an Internal Spiral Tissue Expander Generates New Subcutaneous Adipose Tissue in an In Vivo Animal Model

BACKGROUND

Tissue expanders are widely utilized in plastic surgery. Traditional expanders usually are "inflatable balloons," which are planned to grow additional skin and/or to create space to be filled, for example, with an implant. In very recent years, reports suggest that negative pressure created by an external device (ie, Brava) induces both skin expansion and adipogenesis.

OBJECTIVES

The authors evaluated and assessed the adipogenetic potential of a novel internal tissue expander in an in vivo animal model.

METHODS

New Zealand female rabbits were enrolled in the study. A prototype spiral inner tissue expander was employed. It consisted of a-dynamic conic expander (DCE) with a valve at the end: when empty, it is flat (Archimedean spiral), whereas when filled with a fluid, it takes a conic shape. Inside the conic spiral, a negative pressure is therefore created. DCE is implanted flat under the latissimus dorsi muscle in experimental animals (rabbit) and then filled to reach the conical shape. Animals were investigated with magnetic resonance imaging, histology, and transmission electronic microscopy at 3, 6, and 12 months.

RESULTS

Magnetic resonance imaging revealed a marked increase in newly formed adipose tissue, reaching its highest amount at 12 months after the DCE implantation. Histology confirmed the existence of new adipocytes, whereas transmission electronic microscopy ultrastructure confirmed that most of these new cells were mature adipocytes.

CONCLUSIONS

Tensile stress, associated with negative-pressure expanders, generated newly white subcutaneous adipose tissue.

Application of Fat Grafting in Cosmetic Breast Surgery

The role of fat grafting to the breasts has evolved in the recent past, gaining several new applications within both reconstructive and aesthetic surgery. Initially used for reconstructive purposes to fill lumpectomy defects or to correct residual contour deformities after breast reconstruction, it has since made its way into cosmetic breast surgery and has grown to encompass a wide variety of new indications. Fat grafting in aesthetic breast surgery may be performed as a form of primary autologous breast augmentation or as an adjunct to implant-based breast augmentation to disguise implant edges. It may also be used to provide added volume after explant surgery or to provide improvements in breast contour alongside mastopexy techniques. In this article, we will review the current applications of fat grafting in aesthetic breast surgery and provide an up-to-date summary of its reported outcomes, safety, and complications.

The Science of Fat Grafting

Autologous fat grafting has become a popular and well-established technique used by plastic surgeons in a variety of aesthetic and reconstructive procedures. An understanding of the basic science principles underlying fat grafting is crucial to explaining its extensive utility for soft tissue rejuvenation, volume augmentation, and body contouring-and the unpredictable fat resorption rates after grafting that pose a significant challenge for plastic surgeons. While the scientific principles of fat grafting can theoretically be exploited to optimize fat grafting techniques and increase fat tissue survival, a consensus has yet been established as to the best practices for this procedure. This review discusses the biology of adipose tissue and the scientific principles behind its behavior and survival in autologous fat grafting.

Application of External Force Regulates the Migration and Differentiation of Adipose-Derived Stem/Progenitor Cells by Altering Tissue Stiffness

Large soft-tissue defects are challenging to reconstruct surgically. Expansion of soft tissue using an external volume expansion (EVE) device is a noninvasive method to improve such reconstruction; however, the underlying mechanism is unclear. In this study, we created fat flaps in Sprague-Dawley rats, applied an external force of 3 or 6 kPa using an EVE device, and investigated the migration and differentiation of adipose-derived stem/progenitor cells (ASCs). In addition, we performed finite element analysis to explore the stiffness of adipose tissue. An external force of 3 kPa promoted the migration and adipogenic differentiation of ASCs. By comparison, an external force of 6 kPa had a larger effect on migration of ASCs, but a smaller effect on adipogenic differentiation of ASCs. External force affected adipose tissue stiffness. In conclusion, external force generated by an EVE device increases the stiffness of adipose tissue, which influences the migration and differentiation of ASCs. The size of the external force can be altered according to the tissue stiffness required at particular time points to promote long-term adipose tissue regeneration. Impact Statement Stem cell therapy in clinic mostly requires the addition of exogenous stem cells, therefore the safety and controllability is always defective. In this study, the external force of external volume expansion regulates adipose-derived stem/progenitor cells (ASCs) migration and differentiation through tissue stiffness. Using tissue engineering without exogenous ASCs can promote long-term adipose tissue regeneration. The findings of this study provide theoretical support for clinical tissue engineering applications and improvements in stem cell therapy.

Principles and Applications of Fat Grafting in Plastic Surgery

Autologous fat transplantation has become increasingly popular in recent years. Its biocompatable properties and availability made it a widely used treatment modality for soft tissue augmentation and volume replacement in both reconstructive and aesthetic plastic surgery. Multiple protocols and clinical applications have been described in the literature, with wide variations in the harvesting, processing, and injection techniques. In this review, the authors will discuss the basic principles and clinical applications of fat grafting in plastic and reconstructive surgery. The article will then conclude with a discussion of fat grafting limitations as well as potential future applications, giving the reader a well-rounded understanding of autologous fat transfer.

The Impact of Recipient Site External Expansion in Fat Grafting Surgical Outcomes

Background:

The fat grafting process includes the 4 phases of tissue harvesting, processing, recipient-site preparation, and reinjection. Among them, the preparation of the recipient site has never been exhaustively reviewed. We aim to provide a comprehensive overview of the methods to prepare the recipient site through external expansion with the resulting outcomes.

Methods:

PubMed/Medline database was searched for studies on fat grafting recipient site preparation by applying the following algorithm: ((fat grafting) OR (lipofilling) OR (lipograft) AND (recipient site)). A priori criteria were used to review the resulting articles and identify those dealing with external expansion.

Results:

Fourteen studies published from 2008 through 2016 met inclusion criteria (4 case reports, 6 retrospective, and 4 prospective studies), representing 1,274 treated patients. Two devices for preexpansion were used with different protocols: BRAVA system and Kiwi VAC-6000M with a PalmPump. The 13 studies that applied the BRAVA system reported large fat volume transplantation to the breast (average > 200 cc). The most common complications were localized edema (14.2%), temporary bruising, and superficial skin blisters (11.3%), while the most serious was pneumothorax (0.5%). The majority of the studies reported enhancement of fat graft survival, which ranged between 53% and 82% at 6 months to 1 year follow-up, and high satisfaction of patients and surgeon.

Conclusions:

External expansion and fat grafting is a promising technique for breast reconstruction and augmentation. However, due to the overall low level of evidence of the available studies, further research is needed to validate the procedure.

Recent Advances on the Application of Negative Pressure External Volume Expansion in Breast Plastic Surgery

BACKGROUND

External volume expansion (EVE) has been effectively applied as an assistance to fat transplantation on breast plastic surgery. Many indicators and refinements have been made in clinical practice; meanwhile, the related mechanism and more optimized preclinical model also have been explored in experimental studies.

METHODS

A literature search was conducted using PubMed with the keywords: EVE, negative pressure, breast enlargement, breast augmentation, breast reconstruction, breast plastic surgery and breast aesthetic surgery. Studies dealing with the clinical and preclinical aspects of the subject and also in vitro experiments related to a certain period of negative pressure and adipose-derived cells were selected, and those only focused on negative pressure were excluded.

RESULTS

The indications, contraindications, complications and treatments of EVE in clinical practice were summarized. The experimental studies were mainly classified into two groups (mechanical and translational) according to their contents. Mechanical studies were further divided into inference experimental validation phase studies. For the experimental validation phase, EVE was verified to promote angiogenesis, while it still remained controversial whether it would enhance adipogenesis and cell proliferation.

CONCLUSION

Clinically, our experience is on the stage of exploration, and there is a lack of standardized guidelines on its clinical application. Experimentally, the previous studies showed some subtly different views on the functional mechanisms. However, it is not enough to regulate the clinical practice yet. Therefore, related basic studies and long-term clinical follow-up are needed.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Soft Tissue Reconstruction

Autologous fat transplantation has revolutionized soft tissue reconstruction, but conventional methods remain unpredictable as graft resorption rates are high due to lack of vascularization. The advent of adipose-derived stem cells (ASCs) has led to improvement of fat grafting outcomes, in part to their ability to undergo facile differentiation into adipose tissue, their angiogenic properties, and their ability to express and secrete multiple growth factors. This chapter discusses the isolation and characterization of human ASCs, its expansion in vitro, and relevant in vivo models for adipose tissue engineering.

Management of Tuberous Breast Deformities: Review of Long-term Outcomes and Patient Satisfaction with BREAST-Q

BACKGROUND

The treatment of a tuberous breast deformity has changed over the years, with a large variety of procedures described. However, maintaining a long-lasting breast contour is an ongoing challenge. The aim of this study was to evaluate the long-term results of tuberous breast corrections, focusing on the incidence of secondary procedures and patient satisfaction.

MATERIALS AND METHODS

Forty-six patients who underwent correction of a tuberous breast deformity from 2000 through 2013 were considered. Age, degree of deformity, asymmetry, BMI, pregnancy, first surgical technique used, complications and further surgical procedures were evaluated. Statistical analysis was conducted to identify predicting factors for multiple procedures. Patient satisfaction was evaluated with BREAST-Q.

RESULTS

Eighty-eight breasts were treated: 57 breasts underwent implant-based corrections, whereas 31 breasts underwent autologous procedures. A multi-step procedure was initially planned in 7 breasts only, and 41 breasts underwent secondary procedures: 33 out of 53 breasts (62.3%) were re-operated in the implant-based group, whereas 8 out of 28 breasts (28.6%) were re-operated in the autologous group. Statistical analysis showed a correlation between the number of procedures and young age (P = 0.0253) and between the number of procedures and the primary surgical technique (P = 0.0132). The BREAST-Q evaluation suggested that patient satisfaction was comparable.

CONCLUSIONS

The question of time is one of the main issues in breast surgery. The management of tuberous breast deformities requires a customized strategy considering all parameters to improve the longevity of the result in the long term.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Fat Grafting to the Breast: Clinical Applications and Outcomes for Reconstructive Surgery

This article is a review of fat grafting for breast reconstruction. The use of small volume fat grafting for the correction of step-off deformities, intrinsic deformities, and extrinsic deformities of the breast, and the uses of large volume fat grafting for total breast reconstruction, correction of implant complications with simultaneous implant exchange with fat, and correction of noncancer chest wall deformities is reviewed. Cancer monitoring and the risks of cancer recurrence following fat-grafting to the breast is also reviewed.

Reconstruction of gluteal deformities: a systematic review and experience of four cases

BACKGROUND

The reconstruction of gluteal deformities remains a major challenge. The aim of this article is to provide a systematic review of the literature concerned, and to present a case series with representative defects from various zones.

METHODS

A review of the literature was performed using PubMed, EMBASE, and The Cochrane Library, in accordance with the PRISMA statement. Quality of evidence was rated according to GRADE. Patients with various buttock deformities were included and, depending on the defect, the reconstructive techniques applied consisted of lipoinjection, local fasciocutaneous flap, or pedicled gracilis muscle flap. Complications, patient's pain assessment, impairment in everyday-life activities, aesthetic outcome, objective assessment of sensitivity, and recurrence were considered.

RESULTS

A total of 498 records were identified in the literature search. Of those, 12 studies met the PICOS (participants, interventions, comparators, outcomes, and study design) criteria. Overall, 41 patients were analysed, the evidence of which was of low quality. In this study, four patients (three female and one male) with a mean age of 44 ± 15 years were operated on between 2010-2014. The mean operation time was 83 ± 30 minutes. One patient required revision due to persistent seroma and recurrence, and one patient required neurolysis and gracilis denervation due to neuroma and scarring. After a mean follow-up of 40 ± 21 months, the results were functionally and cosmetically satisfactory.

CONCLUSIONS

Reconstruction of buttock deformities using an integrated approach can lead to a long-lasting, functionally and aesthetically satisfactory result. However, evidence is limited due to the lack of good-quality studies.

Men at risk for paradoxical adipose hyperplasia after cryolipolysis

Cryolipolysis, an aesthetic procedure that reduces adipose tissue by exposure to cold temperature, is generally well tolerated with mild side effects including temporary numbness, erythema, and tenderness. However, as cryolipolysis is gaining popularity and more treatments are being performed, reports of rare adverse events including delayed onset pain and paradoxical adipose hyperplasia (PAH) have been described. Recent studies have suggested that PAH can be more common than expected and have a predilection for males, as a disproportionate number of the cases reported in the literature have occurred in men despite the fact that fewer men are likely to be treated with cryolipolysis. Sexual dimorphism in adipose anatomy may provide insight into the increased susceptibility of men to PAH. Careful patient selection avoiding men with visceral abdominal adipose and firm, nondistensible, fibrous fat may be important to minimize the risk of PAH.

Microenvironmental Control of Adipocyte Fate and Function

The properties of tissue-specific microenvironments vary widely in the human body and demonstrably influence the structure and function of many cell types. Adipocytes are no exception, responding to cues in specialized niches to perform vital metabolic and endocrine functions. The adipose microenvironment is remodeled during tissue expansion to maintain the structural and functional integrity of the tissue and disrupted remodeling in obesity contributes to the progression of metabolic syndrome, breast cancer, and other malignancies. The increasing incidence of these obesity-related diseases and the recent focus on improved in vitro models of human tissue biology underscore growing interest in the regulatory role of adipocyte microenvironments in health and disease.

External Volume Expansion Modulates Vascular Growth and Functional Maturation in a Swine Model

Despite increasing application of the pre-grafting expansion during autologous fat transplantation in breast reconstruction, little is known about its mechanism of action. To address that, ventral skins of miniature pigs were treated over a 10-day or 21-day period, with continuous suction at −50 mm Hg via a 7-cm diameter rubber-lined suction-cup device. Soft tissue thickness increased immediately after this external volume expansion (EVE) treatment, such increase completely disappeared by the next day. In the dermis and subcutaneous fat, the EVE treated groups showed significant increases in blood vessel density evident by CD31 staining as well as in vascular networks layered with smooth muscle cells when compared with the control group. This finding was corroborated by the increased percentage of endothelial cells present in the treatment groups. There was no significant difference in the percentages of proliferating basal keratinocytes or adipocytes, nor in epidermal thickness. Moreover, the EVE had no effect on proliferation or differentiation potential of adipose stem cells. Taken together, the major effects of EVE appeared to be vascular remodeling and maturation of functional blood vessels. This understanding may help clinicians optimize the vascularity of the recipient bed to further improve fat graft survival.

Mechanobiology and Mechanotherapy of Adipose Tissue-Effect of Mechanical Force on Fat Tissue Engineering

Our bodies are subjected to various mechanical forces, which in turn affect both the structure and function of our bodies. In particular, these mechanical forces play an important role in tissue growth and regeneration. Adipocytes and adipose-derived stem cells are both mechanosensitive and mechanoresponsive. The aim of this review is to summarize the relationship between mechanobiology and adipogenesis. PubMed was used to search for articles using the following keywords: mechanobiology, adipogenesis, adipose-derived stem cells, and cytoskeleton. In vitro and in vivo experiments have shown that adipogenesis is strongly promoted/inhibited by various internal and external mechanical forces, and that these effects are mediated by changes in the cytoskeleton of adipose-derived stem cells and/or various signaling pathways. Thus, adipose tissue engineering could be enhanced by the careful application of mechanical forces. It was shown recently that mature adipose tissue regenerates in an adipose tissue-engineering chamber. This observation has great potential for the reconstruction of soft tissue deficiencies, but the mechanisms behind it remain to be elucidated. On the basis of our understanding of mechanobiology, we hypothesize that the chamber removes mechanical force on the fat that normally impose high cytoskeletal tension. The reduction in tension in adipose stem cells triggers their differentiation into adipocytes. The improvement in our understanding of the relationship between mechanobiology and adipogenesis means that in the near future, we may be able to increase or decrease body fat, as needed in the clinic, by controlling the tension that is loaded onto fat.

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.

Shaping of the Unaffected Breast with Brava-Assisted Autologous Fat Grafting to Obtain Symmetry after Breast Reconstruction

BACKGROUND

In breast reconstruction, symmetry is a vital issue. However, when the original breast is unusually shaped or the patient desires augmentation at the time of reconstruction, obtaining symmetrical breasts becomes difficult.

OBJECTIVES

The authors performed shaping of unaffected breasts by Brava-assisted autologous fat grafting to enhance breast symmetry, and evaluated the clinical results to validate this new approach.

METHODS

Brava-assisted autologous fat grafting was performed to the unaffected breasts of 12 patients who had undergone unilateral breast reconstruction. The procedure was used for augmentation in six patients and to correct ptosis, volume, and tuberous breast deformity in three, two, and one patient, respectively. Clinical outcomes were assessed in all 12 patients.

RESULTS

All patients could complete fat grafting within two sessions (one session in nine patients and two sessions in three patients). The mean volume of grafted fat per session was 211 cc in all patients. The mean retention rate of grafted fat was 58.9% in the 10 patients for whom the retention rate could be calculated using preoperative and postoperative magnetic resonance imaging (MRI). Postoperative MRI revealed small benign foci in two patients (16.7%), which were not palpable and did not become a clinical problem. A postoperative mammography revealed a small agglutinate calcification in one patient, which was determined to be benign through biopsy.

CONCLUSIONS

Shaping the unaffected breast by autologous fat grafting combined with Brava is predictable, effective, and feasible as an aesthetic adjunct to unilateral breast reconstruction to achieve breast symmetry.

LEVEL OF EVIDENCE

4 Therapeutic.

Diffusion and perfusion: the keys to fat grafting

BACKGROUND

Fat grafting is now widely used in plastic surgery. Long-term graft retention can be unpredictable. Fat grafts must obtain oxygen via diffusion until neovascularization occurs, so oxygen delivery may be the overarching variable in graft retention.

METHODS

We studied the peer-reviewed literature to determine which aspects of a fat graft and the microenvironment surrounding a fat graft affect oxygen delivery and created 3 models relating distinct variables to oxygen delivery and graft retention.

RESULTS

Our models confirm that thin microribbons of fat maximize oxygen transport when injected into a large, compliant, well-vascularized recipient site. The "Microribbon Model" predicts that, in a typical human, fat injections larger than 0.16 cm in radius will have a region of central necrosis. Our "Fluid Accommodation Model" predicts that once grafted tissues approach a critical interstitial fluid pressure of 9 mm Hg, any additional fluid will drastically increase interstitial fluid pressure and reduce capillary perfusion and oxygen delivery. Our "External Volume Expansion Effect Model" predicts the effect of vascular changes induced by preoperative external volume expansion that allow for greater volumes of fat to be successfully grafted.

CONCLUSIONS

These models confirm that initial fat grafting survival is limited by oxygen diffusion. Preoperative expansion increases oxygen diffusion capacity allowing for additional graft retention. These models provide a scientific framework for testing the current fat grafting theories.

[Fat grafting to improve severe tuberous breast]

INTRODUCTION

Tuberous breast is a rare malformation that has major, negative physical and psychological impacts during puberty. A range of surgical techniques has been used to correct breast shape and volume in this context. Most techniques are based on a combination of skin plasty and mammary gland remodelling, in order to redistribute volumes. Prostheses and local-regional flaps can also be used to correct the missing volume. Fat grafting to the breast has been used in our department since 1998 as a complementary technique in breast reconstruction; it constitutes a natural way of providing volume and modifying the shape of the breast. Since 2000, we have extended this lipomodelling technique to the correction of thorax malformations in general and tuberous breasts in particular. Here, we describe our experience of the correction of severe tuberous breasts by fat grafting.

PATIENTS AND METHODS

Over an 11-year period, we performed a retrospective study on tuberous breast patients treated solely with fat grafting (i.e. without using an implant). Each breast deformation was graded according to the Grolleau classification. After aspiration, the fat was centrifuged and then transferred with a specific cannula. Using an 18-G trocar, we sometimes also performed fasioctomies to free up fibrous bridges and mammary gland remodelling. We evaluated the lipofilling for each case (number of sessions and mean fat transfer volume). Technical efficacy was evaluated in terms of patient's satisfaction and the surgeon's opinion. Safety was evaluated by screening for recipient site complications.

RESULTS

We performed a retrospective study of 31 cases of tuberous breasts treated between January 2000 and December 2010. The severe tuberous breasts were type 3 in 10 cases. The mean patient age was 21 and the mean body mass index was 21.5. Two session (mean transfer volume: 380 cc) were required in every case. The mean follow-up period after the last fat transfer session was 6 years (range: 1-11). The patients were very satisfied in 90% of cases (n=9) and satisfied in 10% of cases (n=1). No complications were observed. Imaging performed before surgery and one year afterwards did not reveal any anomalies, other than oil cysts.

CONCLUSION

The treatment of severe tuberous breast with fat grafting is a reliable technique that produces excellent results and high levels of patient satisfaction. The aesthetic outcome is natural, implant-free and long-lasting. Fat grafting decreases local fibrosis and helps (along with fasciotomies and mammary gland remodelling) modify the shape of the breast. The technique corrects the missing volume in a precise, personalized manner. Lipomodelling efficacy and absence of complications have made it our reference treatment for the correction of severe tuberous breasts (as long as the patient has sufficient adipose reserves).

Adipose-derived stem cells: methods for isolation and applications for clinical use

Adipose tissue sciences have rapidly expanded since the identification of regenerative cells contained within the stromal vascular fraction (SVF) of fat. Isolation of the SVF, containing adipose-derived stem cells (ADSC), can be accomplished efficiently in the operating room or in the laboratory through enzymatic digestion of the adipose tissue and concentration of SVF. Cells can be directly re-injected as a mesotherapeutic agent, recombined with a tissue scaffold (e.g., cell-enriched fat grafts) or expanded in culture for tissue-engineered cell therapeutics. The potential for cell therapy is under current investigation by researchers around the world. This chapter reviews laboratory methods for isolating ADSCs and the ongoing clinical trials evaluating cell therapeutic efficacy across many specialties, including cardiology, neurology, immunology, tissue engineering, sports medicine, and plastic and reconstructive surgery.

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.