A Comparison of Fat Graft Processing Techniques: Outcomes in 1,158 Procedures in Prosthetic Breast Reconstructions

Proliferation Patterns of MCF-7 Breast Cancer Cells in Lipoaspirate Conditioned Media

INTRODUCTION

Autologous fat grafting (AFG) is a common technique used to enhance aesthetic outcomes in postmastectomy breast reconstruction patients. Adipokines are hormones secreted by adipose tissue that play a critical role in regulating metabolic processes and the immune system. However, dysregulated adipokine secretion and signaling can contribute to the development and progression of cancer by promoting angiogenesis, altering the immune response, and inducing the epithelial mesenchymal transition. We aimed to assess how breast cancer cells behave in conditioned media derived from fat grafting lipoaspirates and gain a better understanding of the potential interactions that may occur within the tumor microenvironment.

METHODS

Patients who were undergoing AFG as a part of breast reconstruction at NY-Presbyterian/Weill Cornell Medical Center between March 2021 and July 2023 were consented and enrolled in the study. This study was approved by the Weill Cornell Medicine Institutional Review Board (#20-10022850-14). Conditioned media is created using 20% of patient lipoaspirate secretome and 80% starving media. The growth of MCF-7, a human ER/PR+ breast cancer cell line, in conditioned media is assessed using CyQUANT.

RESULTS

The breast cancer cells incubated in conditioned media displayed similar growth trends as those in complete media, which is enriched for cell growth (P > 0.05). MCF-7 cell behavior in conditioned media differed significantly from their proliferation patterns when serum starved in 100% starving media (P < 0.05).

DISCUSSION

Our results suggest that there may be inherent factors within the lipoaspirate that may promote MCF-7 proliferation. One potential implication is that AFG used for breast reconstruction should be delayed until local-regional disease control has been established. In addition, based on the in vitro proliferation patterns of breast cancer cells in conditioned media, the safety profile of AFG may be enhanced if the procedure is performed after attaining negative margins and the completion breast cancer treatment.

Assessing Long-Term Volume Retention in Breast Fat Grafting: A Comparative Study of Lipoaspirate Processing Techniques

INTRODUCTION

Autologous fat grafting is a method of improving aesthetic outcomes after both breast reconstruction and aesthetic surgery through volume enhancement and tissue contouring. Long-lasting effects are linked to greater patient satisfaction and more optimal augmentation results. Harvesting, processing, and injection techniques may all affect the longevity of deformity filling. Our objective is to evaluate the effect of lipoaspirate processing modality on longitudinal volume retention after surgery.

METHODS

A prospective, single-institution, randomized control trial placed consented postmastectomy fat grafting patients into 1 of 3 treatment arms (active filtration, low-pressure decantation, and standard decantation) in a 1:1:1 ratio. A preoperative 3-dimensional scan of the upper torso was taken as baseline. At the 3-month postoperative visit, another 3D scan was taken. Audodesk Meshmixer was used to evaluate the volume change.

RESULTS

The volume of fat injected during the initial procedure did not differ significantly between the treatment arms (P > 0.05). Both active filtration and low-pressure decantation resulted in higher percentage volume retention than traditional decantation (P < 0.05). Active filtration and low-pressure decantation exhibited comparable degrees of fat maintenance at 3 months (P > 0.05).

DISCUSSION

Compared with using traditional decantation as the lipoaspirate purification technique, active filtration and low-pressure decantation may have led to higher levels of cell viability by way of reduced cellular debris and other inflammatory components that may contribute to tissue resorption and necrosis. Further immunohistochemistry studies are needed to examine whether active filtration and low-pressure decantation lead to lipoaspirates with more concentrated viable adipocytes, progenitor cells, and factors for angiogenesis.

In Vitro Characterization of Fat Grafts Processed Using the REVOLVE ENVI System versus Decantation

Background

This preclinical study evaluated benchtop/in vitro properties and fat viability and activity of grafts processed using the REVOLVE ENVI 600 system compared with decantation and evaluated properties of REVOLVE ENVI waste.

Methods

Lipoaspirate from six donors was processed using REVOLVE ENVI or decantation. The composition of each graft, hematocrit/red blood cell content, fat particle size/macrostructure, viable adipocyte count, and adipocyte activity were analyzed. Stromal vascular fraction was analyzed for viable progenitor cell count and colony-forming units.

Results

REVOLVE ENVI grafts had a higher mean (±SD) fat content at 85.6% ± 6.1% than decanted grafts at 72.1% ± 4.0% (P < 0.001), with negligible free oil (0.4% ± 1.1%) and cellular debris (<0.1%), whereas REVOLVE ENVI waste contained primarily aqueous fluid (91.0% ± 2.2%) with negligible viable fat. REVOLVE ENVI grafts had significantly lower hematocrit levels (P < 0.001) and contained significantly more large fat globules (P < 0.001) than decanted grafts or REVOLVE ENVI waste. The percentage of tissue particles of more than 1000 µm was highest for REVOLVE ENVI grafts at 61.6% ± 9.2% (decantation: 52.5% ± 13.4%; REVOLVE ENVI waste: 0.49% ± 1.50%), and the percentage of particles less than 200 µm was lowest for REVOLVE ENVI grafts at 15.7% ± 2.6% (decantation: 32.2% ± 8.9%; REVOLVE ENVI waste: 97.9% ± 4.5%). REVOLVE ENVI grafts contained 145.2% ± 36.0% more viable adipocytes, 145.7% ± 46.2% greater activity, 195.5% ± 104.2% more progenitors in SVF, and 363.5% ± 161.2% more SVF colony-forming units than decanted grafts.

Conclusion

Fat grafts processed using REVOLVE ENVI demonstrated greater viability and activity than decanted grafts in vitro.

Streamlining the Fat: A Systematic Review of Active Closed Wash and Filtration in Autologous Fat Grafting After Breast Reconstruction

Although fat grafting in breast reconstruction continues to grow in popularity, the optimal technique remains elusive and outcomes are varied. This systematic review of available controlled studies utilizing active closed wash and filtration (ACWF) systems sought to examine differences in fat processing efficiency, aesthetic outcomes, and revision rates. A literature search was performed from inception to February 2022 following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) in Ovid MEDLINE (Wolters Kluwer, Alphen aan den Rijn, the Netherlands), Ovid Embase (Wolters Kluwer), and Cochrane Library (Wiley, Hoboken, NJ). Two independent reviewers screened the studies for eligibility with Covidence software. Bibliographies and citing references from selected articles were screened from Scopus (Elsevier, Amsterdam, the Netherlands). The search identified 3476 citations, with 6 studies included. Three studies demonstrated a significantly higher volume of graftable fat harvested in a significantly lower mean grafting time with ACWF than with their respective controls. With respect to adverse events, 3 studies reported significantly lower incidences of nodule or cyst formation with ACWF with respect to control. Two studies reported a significantly lower incidence of fat necrosis with ACWF vs control, with this trend upheld in 2 additional studies. Three studies reported significantly lower revision rates with ACWF with respect to control. No study reported inferiority with ACWF for any outcome of interest. These data suggest that ACWF systems yield higher fat volumes in less time than other common techniques, with decreased rates of suboptimal outcomes and revisions, thereby supporting active filtration as a safe and efficacious means of fat processing that may reduce operative times. Further large-scale, randomized trials are needed to definitively demonstrate the above trends.

LEVEL OF EVIDENCE: 4

Comparative Analysis of a New Automatic System and Four Existing Techniques for Autologous Fat Grafting

Background

Autologous fat grafting is increasingly used worldwide and is a very attractive technique in many ways. However, treatment duration and postinjection tissue resorption remain problematic elements, which are largely related to the preparation method used. Moreover, few scientific studies objectively compare different fat preparation methods. This study analyzes the efficiency and quality of lipoaspirates prepared with a new filtration/centrifugation system (Adipure) in comparison with several existing techniques.

Methods

Patient lipoaspirates were processed by five different techniques: decantation, centrifugation, Macrofill, Puregraft, and Adipure. Adipose tissue was evaluated in vitro for tissue resorption and oil formation, as well as in vivo after subcutaneous injections in immunodeficient mice. Adipose grafts were collected after 1 month, weighed, and analyzed by histology with a detailed scoring method.

Results

Decanting gives inferior results to all other techniques, in terms of amount of tissue and oil in vitro, or graft weight and histological analysis in vivo. Methods using classical Coleman centrifugation (1200g), or a modified one (400g) associated with washes (Macrofill) produce very similar results, both in vitro and in vivo. Techniques using filtration systems (Puregraft and Adipure) produce less oil overall and have a higher grafting efficiency. The best results regarding grafting efficiency and oil quantity are found with the Adipure device.

Conclusions

A combination of filtration and very low-speed centrifugation potentiates the advantages of these techniques, in terms of graft efficiency. The adipose tissue purification being done in a few minutes, in an automatic way, undoubtedly provides a strong advantage for the use of this new system.

“Achieving Optimal Clinical Outcomes in Autologous Fat Grafting: A Systematic Review of Processing Techniques”

BACKGROUND

Autologous fat grafting (AFG) is a versatile technique in reconstructive and cosmetic surgery. Graft processing is a key source of variability resulting in unreliable clinical outcomes, with no consensus on the optimal methodology. This systematic review identifies the evidence base supporting different processing paradigms.

METHODS

A systematic literature search was conducted using the PubMed, Scopus and The Cochrane Foundation databases. Studies comparing AFG processing methods and reporting long-term patient outcomes were identified.

RESULTS

Twenty-four studies (2413 patients) were identified. Processing techniques evaluated included centrifugation, decantation, washing, filtration, gauze rolling, as well as commercial devices and adipose-derived stem/stromal cell (ASC) enrichment methods. Objective volumetric and subjective patient-reported outcomes were discussed. There was a variable reporting of complications and volume retention rates. Complications were infrequent; palpable cysts (0-20%), surgical-site infections (0-8%) and fat necrosis (0-58.4%) were the most reported. No significant differences in long-term volume retention between techniques were found in AFG in the breast. In head and neck patients, greater volume retention was documented in ASC enrichment (64.8-95%) and commercial devices (41.2%) compared to centrifugation (31.8-76%).

CONCLUSIONS

Graft processing through washing and filtration, including when incorporated into commercial devices, results in superior long-term outcomes compared to centrifugation and decantation methods. ASC enrichment methods and commercial devices seem to have superior long-term volume retention in facial fat grafting.

The Palpable Nodule After Autologous Fat Grafting: Distinguishing Benign Versus Malignant Lesions in a Breast Reconstruction Cohort

BACKGROUND

Nodule formation after autologous fat grafting (AFG) to the breast is the most common complication. In the reconstructive population, this generates significant patient anxiety and presents a diagnostic challenge. We characterized palpable nodule occurrence after AFG in breast reconstruction and compared benign versus malignant nodule characteristics.

METHODS

Chart review of the senior author's experience with breast fat grafting was performed. Data extracted included demographics, intra-operative details, nodule data, radiographic characteristics and biopsy results. Logistic regression identified risk factors for nodule formation. Unpaired t-tests and Fisher's exact tests compared characteristics of benign versus malignant nodules.

RESULTS

In total, 7 75 breasts were identified that underwent 1,158 fat grafting procedures, of which 67 (8.6%) developed palpable nodules. Sonographic characterization of nodules included presumed fat necrosis (38.2%), benign lesion (27.6%), presumed oil cysts (17.1%), indeterminate (8.9%) and concerning for malignancy (8.1%). Lesions concerning for malignancy were more often irregular (10.0% versus 0-2.9% of benign nodules) and more often larger than 0.8 cm in greatest dimension (80% versus 42.9%-61.8% of benign nodules). Six patients developed a palpable local recurrence. Malignant nodules tended to be larger (1.45 cm versus 0.70 cm, p=0.03), were more often vascular (50% versus 3.8%, p=0.03) and tended to occur later (17.5 months versus 10.0 months, p=0.60). Benign nodules occurred in the setting of larger fat graft volumes (64.2 cc versus 40.0 cc, p=0.008).

CONCLUSION

This study provides the first comparison of radiographic and clinical characteristics between benign and malignant palpable nodules post-AFG in breast reconstruction.

The Effect of Lipoaspirate Processing Technique on Complications in Autologous Fat Grafting for Breast Reconstruction: A Propensity Score Analysis Study

BACKGROUND

The use of autologous fat grafting (AFG) is becoming increasingly common as an adjunct to breast reconstruction. However, there is a paucity of data comparing the varying processing devices.

OBJECTIVES

The goal of this study was to compare the outcomes of 2 commercially available AFG processing devices.

METHODS

A retrospective review was conducted of patients who underwent AFG with dual-filter (Puregraft) or single-filter (Revolve) processing systems between 2016 and 2019. Propensity score matching was utilized to adjust for confounding. A total of 38 breasts from the Puregraft group were matched with 38 breasts from the Revolve group.

RESULTS

Matching was successful in achieving a similar distribution of baseline characteristics between the 2 groups. The mean number of AFG sessions was comparable between the 2 groups (P = 0.37) with a similar median total volume (Puregraft, 159 mL vs Revolve, 130 mL; P = 0.23). Complication rates were similar between the 2 devices (Puregraft, 26%; Revolve, 18%; P = 0.47). Patients with at least 1 complication had higher overall AFG volume (median, 200 mL vs 130 mL; P = 0.03) and number of sessions (mean, 2.4 vs 1.8, P = 0.009) compared with those without any postoperative complication.

CONCLUSIONS

Overall complication rates were comparable between 2 commonly used, commercially available AFG processing systems, and therefore the choice of which to use should be based on surgeon preference. Future studies are underway to decipher whether either system offers superior graft retention, cosmetic, or patient-reported outcomes.

LEVEL OF EVIDENCE: 3

Evidence of Browning of White Adipocytes in Poorly Survived Fat Grafts in Patients

BACKGROUND

Browning adipocytes induced by burn and cancer were assumed less viable and more prone to necrosis for their hypermetabolic properties. Recent studies have shown browning of white adipose after fat engraftment in mice.

OBJECTIVES

The authors sought to evaluate whether fat transfer could induce browning biogenesis in fat grafts in humans and if it is associated with graft necrosis.

METHODS

Necrotic adipose grafts were excised from 11 patients diagnosed with fat necrosis after fat grafting or flap transfer. Non-necrotic fat grafts were from 5 patients who underwent revisionary surgeries after flap transfer. Histology and electronic microscopy as well as protein and gene expression of browning-related marker analyses were performed.

RESULTS

Fat grafts with necrosis demonstrated a higher gene expression level of uncoupling protein-1 (greater than fivefold increase, **P < 0.01), a master beige adipocyte marker, than non-necrotic fat grafts. Electronic microscopy and histology showed that browning adipocytes were presented in necrotic adipose in patients.

CONCLUSIONS

Fat transfer induced browning adipocytes in patients and was evident in patients with postgrafting necrosis.

LEVEL OF EVIDENCE: 5

Review of Quantitative Imaging for Objective Assessment of Fat Grafting Outcomes in Breast Surgery

This article presents a comprehensive review of the use of quantitative measurements based on breast images to assess fat retention, breast aesthetics, and fat necrosis after autologous fat grafting. Breast volume measured from MRI and 3-dimensional surface images is widely used as a measure of fat retention. Breast aesthetics are assessed from a combination of anthropometric (distance and contour) measurements on breast surface images. Examination of radiologic images (ultrasonography, mammography, and MRI) is utilized to assess fat necrosis. The article discusses implementation guidelines for objective outcome assessment to support robust quantification and enable investigations of fat grafting efficacy. Level of Evidence: 4.

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

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

Fat Processing Techniques: A Narrative Review

OBJECTIVE

This study reviewed the literature regarding different fat processing techniques, in order to update the information for healthcare personnel and provide the latest evidence in selecting purification methods.

METHODS

PubMed (MEDLINE), EMBASE, the Cochrane Library, and the Cochrane Central Register of Controlled Trials were comprehensively searched to identify studies that compared different fat purification methods for animal and human studies published through July 2020. Papers were screened using inclusion and exclusion criteria, and relative data were collected for review.

RESULTS

A total of 3292 studies were identified, of which 30 were included for review. The findings of existing clinical studies showed that the filtration and washing filtration methods performed better in the volume retention rate of adipose tissue. In terms of postoperative complications (fat necrosis, nodules, cysts, etc.), the incidence of complications of centrifugation is generally higher than that of other purification methods, while Telfa gauze and washing filtration system show better safety. More comparative studies are needed to draw conclusions about clinical efficacy and satisfaction. The existing basic science studies generally believe that centrifugation has no advantage in the integrity and metabolic activity of adipose tissue. However, there is no definite conclusion about the volume retention rate of grafts in animal experiments.

CONCLUSION

In recent years, studies on the cost-effectiveness of various purification methods have emerged, and the efficiency advantages of commercial systems have also been gradually reflected. In the future, the purification efficiency will be improved based on ensuring clinical efficacy, which will be translated into cost savings.

LEVEL OF EVIDENCE III

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 .

Evaluation of a new adipose tissue processing method for breast and buttock fat grafting procedures

Background

There is still some debate about the best adipose processing method for autologous fat transfer procedures. This article reports a series of 66 fat grafting procedures using a novel fat processing technique that involves washing, “micronization,” and decantation.

Methods

We retrospectively reviewed the files of all patients operated on over a 2-year period by the two investigators. They underwent breast or buttock surgery that employed the novel fat processing technique for fat transfer. Complications and patient satisfaction were recorded, and fat resorption was qualitatively assessed based on clinical examination and photographs.

Results

Data were retrieved from a total of 66 procedures performed on 43 patients: 17 breast augmentations, 8 buttock augmentations, and 41 breast reconstructions. Five patients also underwent concomitant facial fat grafting. The complications were one case of transient liponecrotic cyst in the breast, one case of transient areolar sensitivity reduction, and two cases of infection. The infections were reported in patients from the breast reconstruction cohort who had a history of radiotherapy. There was no complication associated with facial fat grafting. Patient satisfaction was achieved in 82.4 to 92.5% of cases depending on the study cohort. Fat resorption was graded as minimal to moderate in 95% of all cases.

Conclusions

This retrospective study supports the safety and effectiveness of this novel fat processing method in breast and buttock surgeries. Further controlled studies are needed to compare its performance with that of other techniques.

Level of evidence: Level III, therapeutic study

Comparative technical analysis of lipoaspirate mechanical processing devices

Fat grafting is a well-established procedure in reconstructive, aesthetic, and regenerative medicine, in particular due to the presence in the adipose tissue of a high concentration of mesenchymal stem cells. The need to reduce fat processing times, for an immediate clinical use and regulatory restrictions on the degree of manipulation of human tissues, has led to the development of numerous devices for the mechanical, nonenzymatic processing of adipose tissue. The aim of this study is to describe the state of the art of mechanical devices used for fat processing, performing a technical analysis of the currently commercially available devices. This should facilitate the development of new devices that improve therapeutic results.