Ultrasound-Assisted Liposuction Does Not Compromise the Regenerative Potential of Adipose-Derived Stem Cells

Intra-Articular Application of Autologous, Fat-Derived Orthobiologics in the Treatment of Knee Osteoarthritis: A Systematic Review

The aim of this study was to review the current literature regarding the effects of intra-articularly applied, fat-derived orthobiologics (FDO) in the treatment of primary knee osteoarthritis over a mid-term follow-up period. A systematic literature search was conducted on the online databases of Scopus, PubMed, Ovid MEDLINE, and Cochrane Library. Studies investigating intra-articularly applied FDO with a minimum number of 10 knee osteoarthritis patients, a follow-up period of at least 2 years, and at least 1 reported functional parameter (pain level or Patient-Reported Outcome Measures) were included. Exclusion criteria encompassed focal chondral defects and techniques including additional arthroscopic bone marrow stimulation. In 28 of 29 studies, FDO showed a subjective improvement in symptoms (pain and Patient-Reported Outcome Measures) up to a maximum follow-up of 7.2 years. Radiographic cartilage regeneration up to 3 years postoperatively, as well as macroscopic cartilage regeneration investigated via second-look arthroscopy, may corroborate the favorable clinical findings in patients with knee osteoarthritis. The methodological heterogeneity in FDO treatments leads to variations in cell composition and represents a limitation in the current state of knowledge. However, this systematic review suggests that FDO injection leads to beneficial mid-term results including symptom reduction and preservation of the affected joint in knee osteoarthritis patients.

Unlocking Potential: Low Bovine Serum Albumin Enhances the Chondrogenicity of Human Adipose-Derived Stromal Cells in Pellet Cultures

Bovine serum albumin (BSA) plays a crucial role in cell culture media, influencing cellular processes such as proliferation and differentiation. Although it is commonly included in chondrogenic differentiation media, its specific function remains unclear. This study explores the effect of different BSA concentrations on the chondrogenic differentiation of human adipose-derived stromal/stem cells (hASCs). hASC pellets from six donors were cultured under chondrogenic conditions with three BSA concentrations. Surprisingly, a lower BSA concentration led to enhanced chondrogenesis. The degree of this effect was donor-dependent, classifying them into two groups: (1) high responders, forming at least 35% larger, differentiated pellets with low BSA in comparison to high BSA; (2) low responders, which benefitted only slightly from low BSA doses with a decrease in pellet size and marginal differentiation, indicative of low intrinsic differentiation potential. In all cases, increased chondrogenesis was accompanied by hypertrophy under low BSA concentrations. To the best of our knowledge, this is the first study showing improved chondrogenicity and the tendency for hypertrophy with low BSA concentration compared to standard levels. Once the tendency for hypertrophy is understood, the determination of BSA concentration might be used to tune hASC chondrogenic or osteogenic differentiation.

Evaluation of Blood Loss in Third-Generation Internal Ultrasound-Assisted Liposuction

BACKGROUND

In large-volume liposuction procedures, one of the most important limitations of total lipoaspirate volume is blood loss. In this study, we aimed to determine the amount of blood loss in individuals who underwent a third-generation internal ultrasound-assisted liposuction (UAL).

METHODS

Eleven female and eleven male participants with a mean age of 35.31 (range 20-47) were included in this prospective study. The third-generation internal UAL was performed on multiple anatomical regions using the VASER® Internal Ultrasound Device (Sound Surgical Technologies; Louisville, CO). The demographic characteristics of the participants, the amount of aspirate collected, and hemoglobin (Hgb) and hematocrit (Htc) values before and after the third-generation internal UAL were evaluated.

RESULTS

The mean third-generation internal UAL time was 74.81 ± 17.95 minutes, and the mean aspiration amount was 5,122.27 ± 1,597.43 ml. The aspirated amount was 6.64% ± 2.20 of body weight. The mean Hgb value was 13.87 ± 1.99 before the third-generation internal UAL and 11.26 ± 2.16 (g/dL) after the third-generation internal UAL (z = 4.108, p < 0.001). The mean reduction in Hgb levels with the third-generation internal UAL was 2.61 ± 1.73 and 0.53 ± 0.36 per liter of aspirate taken. The mean Htc value after the third-generation internal UAL was 33.91 ± 6.03 and was significantly lower than the mean Htc value before the third-generation internal UAL, 41.39 ± 5.13 (z = -3.946, p < 0.001). The mean reduction in Htc with the third-generation internal UAL was 7.48 ± 5.42, and the Htc value decreased by 1.50 ± 1.13 per liter of aspirate ingested. The amount of aspirated supernatant was responsible for 44.4% of the change in Hgb and 30.9% of the change in Htc after the third-generation internal UAL.

CONCLUSION

Knowing the reduction rates in Hgb and Htc with the third-generation internal UAL is useful to plan the amount of aspirate to be taken, the amount of blood loss that may occur with the third-generation internal UAL, and the postoperative care of the patients.

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 .

Arthroscopy with Lipoaspirate and Plasma Infiltration Using Adipose-Derived Stem Cells Plus Platelet-Rich Plasma: Harvesting and Injection for Arthroscopic Treatment of Cartilage Defects of the Knee

Osteoarthritis, predominantly of the knee, is a highly prevalent disease leading to pain, reduced quality of life, and significantly reduced ability to work. With autologous orthobiologic options, new regenerative treatment methods have emerged, offering an alternative to early surgical intervention. Supercharged Liparthroplasty combines arthroscopy with lipoaspirate and plasma infiltration of the joint. Lipoaspirate contains high levels of adipose-derived stem cells, which show chondroprotective and anti-inflammatory qualities. Intra-articular injection, combined with platelet-rich plasma administration for accelerated cartilage metabolism, thus provides an optional approach in osteoarthritis treatment. This article aims to provide in detail our regimen for Supercharged Liparthroplasty, including tissue harvesting and preparation of the injectables, therefore enabling physicians to adopt this point-of-care technique.

Therapeutic potential of adipose tissue derivatives in skin photoaging

Photoaging, the primary cause of exogenous skin aging and predominantly caused by ultraviolet radiation, is an essential type of skin aging characterized by chronic skin inflammation. Recent studies have shown that oxidative stress, inflammation, skin barrier homeostasis, collagen denaturation and pigmentation are the main contributors to it. As a composite tissue rich in matrix and vascular components, adipose tissue derivatives have been recently gaining attention as potential therapeutic agents for various human diseases with fat-processing technology upgrades. This review analyzes both 'minimally treated' and 'nonminimally treated' fat derivatives to give an overview of the preclinical and clinical relevance of adipose tissue derivatives for antiphotoaging application, highlighting their good clinical prospects as well as discussing their safety and potential risks.

Comparison of therapeutic effects of mesenchymal stem cells derived from superficial and deep subcutaneous adipose tissues

BACKGROUND

Fibrosis is a common histological feature in the process from chronic organ injury to organ failure. Chronic tissue injury causes inflammatory cell infiltration into the injured tissue. The persistence of this inflammatory cell infiltration leads to fibrosis and organ failure. Adipose-derived mesenchymal stem cells (ASCs) have received much attention as a regenerative therapeutic tool to prevent progression from organ injury to failure. Subcutaneous abdominal adipose tissue is divided into superficial and deep layers by a superficial fascia. Adipose tissue easily collected by liposuction is usually obtained from a deep layer, so ASCs derived from a deep layer are generally used for regenerative medicine. However, no research has been conducted to investigate differences in the therapeutic effects of ASCs from the superficial and deep layers (Sup-ASCs and Deep-ASCs, respectively). Therefore, we compared the therapeutic potencies of Sup-ASCs and Deep-ASCs.

METHODS

ASCs were isolated from superficial and deep subcutaneous abdominal adipose tissues collected from patients who underwent breast reconstruction. We first compared cell characteristics, such as morphology, cell proliferation, cell surface markers, adipogenic and osteogenic differentiation, cell senescence markers, and expression of coagulation and anticoagulant factors between Sup-ASCs and Deep-ASCs. Furthermore, we compared their ability to promote polarization of M2 macrophages and to inhibit transforming growth factor (TGF)-β/Smad signaling using THP-1 cells and TGF-β1 stimulated HK-2 cells incubated with conditioned media from Sup-ASCs or Deep-ASCs. In in vivo experiments, after renal ischemia-reperfusion injury (IRI) procedure, Sup-ASCs or Deep-ASCs were injected through the abdominal aorta. At 21 days post-injection, the rats were sacrificed and their left kidneys were collected to evaluate fibrosis. Finally, we performed RNA-sequencing analysis of Sup-ASCs and Deep-ASCs.

RESULTS

Sup-ASCs had greater proliferation and adipogenic differentiation compared with Deep-ASCs, whereas both ASC types had similar morphology, cell surface markers, senescence markers, and expression of coagulation and anticoagulant factors. Conditioned media from Sup-ASCs and Deep-ASCs equally promoted polarization of M2 macrophages and suppressed TGF-β/Smad signaling. Moreover, administration of Sup-ASCs and Deep-ASCs equally ameliorated renal fibrosis induced by IRI in rats. RNA-sequencing analysis revealed no significant difference in the expression of genes involved in anti-inflammatory and anti-fibrotic effects between Sup-ASCs and Deep-ASCs.

CONCLUSIONS

These results indicate that both Sup-ASCs and Deep-ASCs can be used effectively and safely as an intravascular ASC therapy for organ injury.

Quality and Vitality of Autologous Fat Grafts Harvested by Different Techniques: A Clinical Comparison Study

BACKGROUND

Unpredictable outcomes with autologous fat grafting due to reabsorption processes present a major challenge for healthcare providers and patients. A higher number of viable adipocytes is considered to result in a higher volume being retained. Although various adverse factors have been extensively researched, other potential parameters have been less investigated or even neglected.

OBJECTIVE

The aim of this study was to investigate the harvesting process of adipose tissue as the primary cause of cell damage and to determine the risk factors associated with low cell survival.

METHODS

Thirty-nine male and female subjects undergoing planned elective liposuction or abdominoplasty were enrolled. Forty-seven lipoaspirates harvested by different liposuction techniques were analyzed. RNA isolation and real-time polymerase chain reaction was performed to elucidate differences in the expression of various adipocyte markers. Furthermore, scanning electron microscopy was performed on various samples to determine the cell damage caused by the different techniques.

RESULTS

A statistically significant lower expression of peroxisome proliferator-activated receptor γ was detected in subjects with a higher BMI. A trend towards a lower expression of perilipin 1 in lipoaspirates harvested by a super wet + ultrasound technique, compared with dry and super wet techniques, was shown. The lowest level of cell damage determined from scanning electron microscopy images was in lipoaspirates harvested by the super wet + ultrasound technique, and this level was statistically significantly different from those obtained by the 2 other techniques.

CONCLUSIONS

Optimization of the outcome in autologous fat grafting may be feasible by targeting and optimizing the harvesting process as a main risk factor for impaired adipocyte viability. Ultrasound-assisted liposuction might be considered a suitable harvesting technique.

LEVEL OF EVIDENCE: 5

Adipose-Derived Stem Cells for Facial Rejuvenation

The interest in regenerative medicine is increasing, and it is a dynamically developing branch of aesthetic surgery. Biocompatible and autologous-derived products such as platelet-rich plasma or adult mesenchymal stem cells are often used for aesthetic purposes. Their application originates from wound healing and orthopaedics. Adipose-derived stem cells are a powerful agent in skin rejuvenation. They secrete growth factors and anti-inflammatory cytokines, stimulate tissue regeneration by promoting the secretion of extracellular proteins and secrete antioxidants that neutralize free radicals. In an office procedure, without cell incubation and counting, the obtained product is stromal vascular fraction, which consists of not only stem cells but also other numerous active cells such as pericytes, preadipocytes, immune cells, and extra-cellular matrix. Adipose-derived stem cells, when injected into dermis, improved skin density and overall skin appearance, and increased skin hydration and number of capillary vessels. The main limitation of mesenchymal stem cell transfers is the survival of the graft. The final outcomes are dependent on many factors, including the age of the patient, technique of fat tissue harvesting, technique of lipoaspirate preparation, and technique of fat graft injection. It is very difficult to compare available studies because of the differences and multitude of techniques used. Fat harvesting is associated with potentially life-threatening complications, such as massive bleeding, embolism, or clots. However, most of the side effects are mild and transient: primarily hematomas, oedema, and mild pain. Mesenchymal stem cells that do not proliferate when injected into dermis promote neoangiogenesis, that is why respectful caution should be taken in the case of oncologic patients. A longer clinical observation on a higher number of participants should be performed to develop reliable indications and guidelines for transferring ADSCs.

[Current status and prospects of clinical application of liposuction]

OBJECTIVE

To review the characteristics and deficiencies of various liposuction methods to provide reference for choosing more suitable liposuction in clinic and ideas for the improvement and development of liposuction equipment.

METHODS

The literature related to liposuction in recent years was consulted, and the principle, indications as well as existing problems were reviewed.

RESULTS

Liposuction can be divided into two categories according to the principles of fat separation. The first type relies on physical cutting to separate fat, including suction-assisted liposuction (SAL), power-assisted liposuction (PAL), and water-assisted liposuction (WAL). SAL and PAL are simple to operate and low in price, but the effect of liposuction mainly depends on the experience of the surgeon, and complications such as uneven appearance, hematoma, and ecchymosis may occur. WAL saves time and effort, but has lower cost performance. The second type relies on energy destruction to separate fat, including ultrasound-assisted liposuction, laser-assisted liposuction, and radiofrequency-assisted liposuction. This type of surgery has the advantages of less trauma, fast postoperative recovery, and skin tightening. However, the equipment is more expensive, and has a risk of skin burns.

CONCLUSION

Liposuction can effectively reduce local fat accumulation, but it still has limitations. Equipment improvement and fat transplantation are important directions for liposuction's future development.

Fate of Fat Grafting In Vivo and In Vitro: Does the Suction-Assisted Lipectomy Device Matter?

BACKGROUND

Recently, there has been increasing research interest in identifying the effect of liposuction procedures on fat graft survival in order to clarify whether different harvest techniques affect the quality of fat grafts.

OBJECTIVES

The aim of this study was to investigate the effect of 2 liposuction methods on the survival and regeneration potential of grafted fat tissue. The proliferation and differentiation potentials of adipose-derived stem cells (ASCs) isolated by both methods was also investigated.

METHODS

Fat grafts were collected from patients who underwent liposuction procedures by 2 different methods: traditional suction-assisted liposuction (TSAL) and vibration amplification of sound energy at resonance (VASER). One portion of the lipoaspirates was implanted into the subcutaneous layer of nu mice for 4 and 12 weeks. ASCs were isolated from the other portion of the lipoaspirate and subjected to proliferation and differentiation assays.

RESULTS

Although in vivo fat grafting presented similar adipose tissue survival for the 2 different liposuction methods, more angiogenesis and less fibrosis was observed in the VASER group based on histologic evaluation. Furthermore, VASER-derived ASCs presented better quality in terms of cell differentiation capacity.

CONCLUSIONS

The in vivo study confirmed better graft angiogenesis with less inflammation, apoptosis, and scar formation in the VASER group. ASCs harvested with VASER exhibited increased differentiation capacity compared with those obtained by TSAL, and represent an excellent source for fat grafting and regenerative medicine.

Comparative proteomic analysis of osteogenic differentiated human adipose tissue and bone marrow-derived stromal cells

Mesenchymal stromal cells are promising candidates for regenerative applications upon treatment of bone defects. Bone marrow‐derived stromal cells (BMSCs) are limited by yield and donor morbidity but show superior osteogenic capacity compared to adipose‐derived stromal cells (ASCs), which are highly abundant and easy to harvest. The underlying reasons for this difference on a proteomic level have not been studied yet. Human ASCs and BMSCs were characterized by FACS analysis and tri‐lineage differentiation, followed by an intraindividual comparative proteomic analysis upon osteogenic differentiation. Results of the proteomic analysis were followed by functional pathway analysis. 29 patients were included with a total of 58 specimen analysed. In these, out of 5148 identified proteins 2095 could be quantified in >80% of samples of both cell types, 427 in >80% of ASCs only and 102 in >80% of BMSCs only. 281 proteins were differentially regulated with a fold change of >1.5 of which 204 were higher abundant in BMSCs and 77 in ASCs. Integrin cell surface interactions were the most overrepresented pathway with 5 integrins being among the proteins with highest fold change. Integrin 11a, a known key protein for osteogenesis, could be identified as strongly up‐regulated in BMSC confirmed by Western blotting. The integrin expression profile is one of the key distinctive features of osteogenic differentiated BMSCs and ASCs. Thus, they represent a promising target for modifications of ASCs aiming to improve their osteogenic capacity and approximate them to that of BMSCs.

Preclinical evaluation for removal of bulging lower eyelid fat using ultrasound-assisted lipolysis on a Yorkshire pig

PURPOSE

The purpose of this study is to evaluate the efficacy and safety of treating lower eyelid fat bulging with ultrasound-assisted lipolysis (UAL) by performing a preclinical evaluation of the procedure on a Yorkshire pig.

METHODS

Two white Yorkshire pigs had lower eyelid fat bulging treated with UAL using a probe with a diameter of 1.0 mm or less. Fourteen days after treatment, we evaluated the changes in fat thickness from ultrasound, changes in skin contour (volume and height) from the Antera 3D™, and the disruption of fat cells and changes in collagen synthesis from histological evaluation.

RESULTS

Fourteen days after treatment, the fat layer was significantly reduced with no damage to the skin surface. The mean change in the subcutaneous fat layer thickness was decreased 1.51-0.75 mm in ultrasound analysis. The skin contour of the treated area also decreased with time from 202.5 to 163.5 mm in mean volume and 0.8111 to 0.646 mm in mean height. Masson's trichrome staining showed that the UAL treatment induced the regeneration and remodeling of collagen.

CONCLUSION

The results of this study demonstrate that UAL successfully reduced the bulging lower eyelid fat of a Yorkshire pig and also increased collagen contraction to tighten skin. UAL may be a beneficial and well-tolerated treatment option for lower eyelid fat bulging.

32 Years of Ultrasonic-Assisted Lipoplasty (U.A.L.): From Aesthetic to Obesity

In this article, we tried to take stock of the state of the art in ultrasonic-assisted lipoplasty focusing on its most recent technologic advances and in the newest clinical applications, such as overweight, obesity, breast surgery and regenerative medicine. Great space was devoted to the analysis and clarification of the most common myths and legends related to this intriguing technique.

Molecular Characterization of Lipoaspirates Used in Regenerative Head and Neck Surgery

Importance

Adipose-derived mesenchymal stem cells (ASCs) have been used commonly in regenerative medicine and increasingly for head and neck surgical procedures. Lipoaspiration with centrifugation is purported to be a mild method for the extraction of ASCs used for autologous transplants to restore tissue defects or induce wound healing. The content of ASCs, their paracrine potential, and cellular potential in wound healing have not been explored for this method to our knowledge.

Objective

To evaluate the characteristics of lipoaspirates used in reconstructive head and neck surgical procedures with respect to wound healing.

Design, Setting, and Participants

This case series study included 15 patients who received autologous fat injections in the head and neck during surgical procedures at a tertiary referral center. The study was performed from October 2017 to November 2018, and data were analyzed from October 2017 to February 2019.

Main Outcomes and Measures

Excessive material of lipoaspirates from subcutaneous abdominal fatty tissue was examined. Cellular composition was analyzed using immunohistochemistry (IHC) and flow cytometry, and functionality was assessed through adipose, osteous, and chondral differentiation in vitro. Supernatants were tested for paracrine ASC functions in fibroblast wound-healing assays. Enzyme-linked immunosorbent assay measurement of tumor necrosis factor (TNF), vascular endothelial growth factor (VEGF), stromal-derived factor 1α (SDF-1α), and transforming growth factor β3 (TGF-β3) was performed.

Results

Among the 15 study patients (8 [53.3%] male; mean [SD] age at the time of surgery, 63.0 [2.8] years), the stromal vascular fraction (mean [SE], 53.3% [4.2%]) represented the largest fraction within the native lipoaspirates. The cultivated cells were positive for CD73 (mean [SE], 99.90% [0.07%]), CD90 (99.40% [0.32%]), and CD105 (88.54% [2.74%]); negative for CD34 (2.70% [0.45%]) and CD45 (1.74% [0.28%]) in flow cytometry; and negative for CD14 (10.56 [2.81] per 300 IHC score) and HLA-DR (6.89 [2.97] per 300 IHC score) in IHC staining; they differentiated into osteoblasts, adipocytes, and chondrocytes. The cultivated cells showed high expression of CD44 (mean [SE], 99.78% [0.08%]) and CD273 (82.56% [5.83%]). The supernatants were negative for TNF (not detectable) and SDF-1α (not detectable) and were positive for VEGF (mean [SE], 526.74 [149.84] pg/mL for explant supernatants; 528.26 [131.79] pg/106 per day for cell culture supernatants) and TGF-β3 (mean [SE], 22.79 [3.49] pg/mL for explant supernatants; 7.97 [3.15] pg/106 per day for cell culture supernatants). Compared with control (25% or 50% mesenchymal stem cell medium), fibroblasts treated with ASC supernatant healed the scratch-induced wound faster (mean [SE]: control, 1.000 [0.160]; explant supernatant, 1.369 [0.070]; and passage 6 supernatant, 1.492 [0.094]).

Conclusions and Relevance

The cells fulfilled the international accepted criteria for mesenchymal stem cells. The lipoaspirates contained ASCs that had the potential to multidifferentiate with proliferative and immune-modulating properties. The cytokine profile of the isolated ASCs had wound healing-promoting features. Lipoaspirates may have a regenerative potential and an application in head and neck surgery.

Level of Evidence

NA.

Isolation of canine adipose-derived mesenchymal stem cells from falciform tissue obtained via laparoscopic morcellation: A pilot study

OBJECTIVE

To evaluate the feasibility of stem cell isolation from falciform fat harvested via laparoscopic morcellation.

STUDY DESIGN

Pilot study.

ANIMALS

Eleven client-owned dogs.

METHODS

Falciform was harvested traditionally via laparotomy and laparoscopically via tissue morcellation. Harvested tissue was processed with a commercially available adipose tissue dissociation kit to obtain a stromal vascular fraction (SVF). Cells were subsequently labeled for CD90, CD45, and CD44 cell surface antigens by using magnetic-activated cell sorting (MACS) and fluorescence-activated cell sorting flow cytometry. CD90⁺ cells were quantitated, and their viability was assessed with a hemocytometer and a trypan blue exclusion test of cell viability.

RESULTS

No perioperative complications occurred in dogs undergoing laparoscopic morcellation. Laparoscopically and traditionally harvested samples yielded an average of 0.39 (±0.1) × 10⁶ and 0.33 (±0.1) × 10⁶ CD90⁺ cells, respectively, per 10 million SVF cells. CD90⁺ cell viability after MACS was 89% (±11%) for morcellated and 86% (±7%) for traditionally harvested samples. Neither CD90⁺ cell quantity nor viability was different between samples obtained via traditional laparotomy vs laparoscopic morcellation (P = .38 and P = .63, respectively). Populations of CD90⁺ cells isolated with each harvest technique had similar CD44 and CD45 expression profiles.

CONCLUSION

Viable populations of CD90⁺ cells with similar CD44/CD45 expression profiles were isolated from laparoscopically morcellated and traditionally harvested falciform tissue. No appreciable morbidity was associated with laparoscopic falciform morcellation.

CLINICAL SIGNIFICANCE

Laparoscopic morcellation is a safe and effective minimally invasive approach to falciform tissue harvest for adipose-derived mesenchymal stem cell isolation.

Wound healing and fibrosis: current stem cell therapies

Scarring is a result of the wound healing response and causes tissue dysfunction after injury. This process is readily evident in the skin, but also occurs internally across organ systems in the form of fibrosis. Stem cells are crucial to the innate tissue healing response and, as such, present a possible modality to therapeutically promote regenerative healing while minimizing scaring. In this review, the cellular basis of scaring and fibrosis is examined. Current stem cell therapies under exploration for skin wound healing and internal organ fibrosis are discussed. While most therapeutic approaches rely on the direct application of progenitor-type cells to injured tissue to promote healing, novel strategies to manipulate the scarring response are also presented. As our understanding of developmental and stem cell biology continues to increase, therapies to encourage regeneration of healthy functional tissue after damage secondary to injury or disease will continue to expand.

Methods and Strategies for Procurement, Isolation, Characterization, and Assessment of Senescence of Human Mesenchymal Stem Cells from Adipose Tissue

Human adipose-derived mesenchymal stem (stromal) cells (hADSC) represent an attractive source of the cells for numerous therapeutic applications in regenerative medicine. These cells are also an efficient model to study biological pathways of stem cell action, tissue injury and disease. Like any other primary somatic cells in culture, industrial-scale expansion of mesenchymal stromal cells (MSC) leads to the replicative exhaustion/senescence as defined by the "Hayflick limit." The senescence is not only greatly effecting in vivo potency of the stem cell cultures but also might be the cause and the source of clinical inconsistency arising from infused cell preparations. In this light, the characterization of hADSC replicative and stressor-induced senescence phenotypes is of great interest.This chapter summarizes some of the essential protocols and assays used at our laboratories and clinic for the human fat procurement, isolation, culture, differentiation, and characterization of mesenchymal stem cells from adipose tissue and the stromal vascular fraction. Additionally, we provide manuals for characterization of hADSC senescence in a culture based on stem cells immunophenotype, proliferation rate, migration potential, and numerous other well-accepted markers of cellular senescence. Such methodological framework will be immensely helpful to design standards and surrogate measures for hADSC-based therapeutic applications.

Fibrin Glue Enhances Adipose-Derived Stromal Cell Cytokine Secretion and Survival Conferring Accelerated Diabetic Wound Healing

Introduction

Although chronic wounds are a major personal and economic burden, treatment options are still limited. Among those options, adipose-derived stromal cell- (ASC-) based therapies rank as a promising approach but are restricted by the harsh wound environment. Here we use a commercially available fibrin glue to provide a deliverable niche for ASCs in chronic wounds.

Material and Methods

To investigate the in vitro effect of fibrin glue, cultivation experiments were performed and key cytokines for regeneration were quantified. By using an established murine chronic diabetic wound-healing model, we evaluated the influence of fibrin glue spray seeding on cell survival (In Vivo Imaging System, IVIS), wound healing (wound closure kinetics), and neovascularization of healed wounds (CD31 immunohistochemistry).

Results

Fibrin glue seeding leads to a significantly enhanced secretion of key cytokines (SDF-1, bFGF, and MMP-2) of human ASCs in vitro. IVIS imaging showed a significantly prolonged murine ASC survival in diabetic wounds and significantly accelerated complete wound closure in the fibrin glue seeded group. CD31 immunohistochemistry revealed significantly more neovascularization in healed wounds treated with ASCs spray seeded in fibrin glue vs. ASC injected into the wound bed.

Conclusion

Although several vehicles have shown to successfully act as cell carrier systems in preclinical trials, regulatory issues have prohibited clinical usage for chronic wounds. By demonstrating the ability of fibrin glue to act as a carrier vehicle for ASCs, while simultaneously enhancing cellular regenerative function and viability, this study is a proponent of clinical translation for ASC-based therapies.

Single-Cell Gene Expression Analysis and Evaluation of the Therapeutic Function of Murine Adipose-Derived Stromal Cells (ASCs) from the Subcutaneous and Visceral Compartment

Introduction

Adipose-derived stromal cells (ASCs) are a promising resource for wound healing and tissue regeneration because of their multipotent properties and cytokine secretion. ASCs are typically isolated from the subcutaneous fat compartment, but can also be obtained from visceral adipose tissue. The data on their equivalence diverges. The present study analyzes the cell-specific gene expression profiles and functional differences of ASCs derived from the subcutaneous (S-ASCs) and the visceral (V-ASCs) compartment.

Material and Methods

Subcutaneous and visceral ASCs were obtained from mouse inguinal fat and omentum. The transcriptional profiles of the ASCs were compared on single-cell level. S-ASCs and V-ASCs were then compared in a murine wound healing model to evaluate their regenerative functionality.

Results

On a single-cell level, S-ASCs and V-ASCs displayed distinct transcriptional profiles. Specifically, significant differences were detected in genes associated with neoangiogenesis and tissue remodeling (for example, Ccl2, Hif1α, Fgf7, and Igf). In addition, a different subpopulation ecology could be identified employing a cluster model. Nevertheless, both S-ASCs and V-ASCs induced accelerated healing rates and neoangiogenesis in a mouse wound healing model.

Conclusion

With similar therapeutic potential in vivo, the significantly different gene expression patterns of ASCs from the subcutaneous and visceral compartments suggest different signaling pathways underlying their efficacy. This study clearly demonstrates that review of transcriptional results in vivo is advisable to confirm the tentative effect of cell therapies.

Autologous fat grafting: Harvesting techniques

Autologous fat grafting is widely used for soft-tissue augmentation and replacement in reconstructive and aesthetic surgery providing a biocompatible, natural and inexpensive method. Multiple approaches have been developed in the past years, varying in the location of adipose tissue donor-sites, use of wetting solutions, harvesting, processing and placing techniques. Despite many advances in this subject, the lack of standardization in the protocols and the unpredictability of the resorption of the grafted tissue pose a significant limitation for graft retention and subsequent filling. In this review, we discuss several approaches and methods described over the last years concerning the harvesting of autologous fat grafts. We focus on contents such as the best donor-site, differences between existing harvesting techniques (namely tissue resection, hand aspiration or liposuction techniques), recommended harvesting cannula diameters, pressure application and volume of wetting solution injected prior aspiration. Results and comparisons between methods tend to vary according to the outcome measured, thus posing a limitation to pinpoint the most efficient methods to apply in fat grafting. Additionally, the lack of a standard assay to determine viability or volume augmentation of fat grafting remains another limitation to obtain universally accepted grafting procedures and protocols.

•

Distinct harvesting procedures associate with different outcomes of fat graft take.

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Flank, abdomen, thigh and knee are the more consistently used donor-sites for fat.

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Higher vacuum pressures in liposuction are more traumatic for the tissue.

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The tumescent technique is a safer procedure with improved aesthetic results.

•

Comparing harvesting techniques is a big challenge given the multiple variables.

Ultrasound-assisted liposuction provides a source for functional adipose-derived stromal cells

BACKGROUND AIMS

Regenerative medicine employs human mesenchymal stromal cells (MSCs) for their multi-lineage plasticity and their pro-regenerative cytokine secretome. Adipose-derived mesenchymal stromal cells (ASCs) are concentrated in fat tissue, and the ease of harvest via liposuction makes them a particularly interesting cell source. However, there are various liposuction methods, and few have been assessed regarding their impact on ASC functionality. Here we study the impact of the two most popular ultrasound-assisted liposuction (UAL) devices currently in clinical use, VASER (Solta Medical) and Lysonix 3000 (Mentor) on ASCs.

METHODS

After lipoaspirate harvest and processing, we sorted for ASCs using fluorescent-assisted cell sorting based on an established surface marker profile (CD34+CD31-CD45-). ASC yield, viability, osteogenic and adipogenic differentiation capacity and in vivo regenerative performance were assessed.

RESULTS

Both UAL samples demonstrated equivalent ASC yield and viability. VASER UAL ASCs showed higher osteogenic and adipogenic marker expression, but a comparable differentiation capacity was observed. Soft tissue healing and neovascularization were significantly enhanced via both UAL-derived ASCs in vivo, and there was no significant difference between the cell therapy groups.

CONCLUSIONS

Taken together, our data suggest that UAL allows safe and efficient harvesting of the mesenchymal stromal cellular fraction of adipose tissue and that cells harvested via this approach are suitable for cell therapy and tissue engineering applications.

Effect of hypoxia on human adipose-derived mesenchymal stem cells and its potential clinical applications

Human adipose-derived mesenchymal stem cells (hASCs) are an ideal cell source for regenerative medicine due to their capabilities of multipotency and the readily accessibility of adipose tissue. They have been found residing in a relatively low oxygen tension microenvironment in the body, but the physiological condition has been overlooked in most studies. In light of the escalating need for culturing hASCs under their physiological condition, this review summarizes the most recent advances in the hypoxia effect on hASCs. We first highlight the advantages of using hASCs in regenerative medicine and discuss the influence of hypoxia on the phenotype and functionality of hASCs in terms of viability, stemness, proliferation, differentiation, soluble factor secretion, and biosafety. We provide a glimpse of the possible cellular mechanism that involved under hypoxia and discuss the potential clinical applications. We then highlight the existing challenges and discuss the future perspective on the use of hypoxic-treated hASCs.

Fat Grafting with Tissue Liquefaction Technology as an Adjunct to Breast Reconstruction

Background

Tissue liquefaction technology (TLT) delivers warmed saline from the liposuction cannula tip at low pressure pulses to disaggregate adipocytes. This technology differs significantly from that used in other liposuction devices including water jet-assisted liposuction. Here we introduce our early experience with this technology in the setting of fat transfer for revision breast reconstruction.

Methods

A retrospective chart review of 136 consecutive patients who underwent fat harvest with TLT and subsequent transfer into 237 breast reconstructions was conducted at a single institution. This two-surgeon series examined donor and recipient site complication rates over a median follow-up of 143 days [87–233].

Results

The overall complication rate was 28.7 %, of which the majority (22.1 %) was fat necrosis at the recipient site as documented by any clinical, imaging, or pathologic evidence. The abdomen served as the donor site for half of the cases. Donor site complications were limited to widespread ecchymosis of the donor site notable in 10.4 % of cases. Twenty-five percent of patients had received postmastectomy radiotherapy prior to fat transfer. Prior to revision with fat transfer, implant-based breast reconstruction was used in 75.5 % of cases, and autologous flaps in the remainder. Fat transfer was combined with other reconstructive procedures 94.1 % of the time.

Conclusions

TLT can be used to harvest adipocytes for fat transfer with donor site morbidity and recipient site complications comparable to other modalities. The efficiency and quality of harvested fat makes this technology appealing for wide spread adoption during fat transfer.

Level of Evidence IV

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Autologous fat transplantation for breast reconstruction: A literature review

INTRODUCTION

The use of autologous fat transplantation to correct volume and contour defects, scars, and asymmetry after breast cancer surgery has increased over the past 20 years. Many developments and refinements in this technique have taken place in recent years, and several studies of the safety of lipofilling in the breast have been published.

PRESENTATION OF CASE

We performed a literature review of this technique, highlighting the crucial role of lipofilling in breast cancer reconstruction.

DISCUSSION

The efficacy of the fat graft transplantation depends on the experience and the technique used by the surgeon. The ASCs (adipose-derived stem cells) contained in the fat graft has proven to be crucial for breast reconstruction by mean the regeneration of tissue, through the chemotactic, paracrine, and immunomodulatory activities and their in situ differentiation.

CONCLUSION

The role of lipofilling for breast reconstruction could be more significant with the application of the findings of experimental research on tissue engineering and ASCs.

Suction assisted liposuction does not impair the regenerative potential of adipose derived stem cells

Background

Adipose-derived stem cells (ASCs) have been identified as a population of multipotent cells with promising applications in tissue engineering and regenerative medicine. ASCs are abundant in fat tissue, which can be safely harvested through the minimally invasive procedure of liposuction. However, there exist a variety of different harvesting methods, with unclear impact on ASC regenerative potential. The aim of this study was thus to compare the functionality of ASCs derived from the common technique of suction-assisted lipoaspiration (SAL) versus resection.

Methods

Human adipose tissue was obtained from paired abdominoplasty and SAL samples from three female donors, and was processed to isolate the stromal vascular fraction. Fluorescence-activated cell sorting was used to determine ASC yield, and cell viability was assayed. Adipogenic and osteogenic differentiation capacity were assessed in vitro using phenotypic staining and quantification of gene expression. Finally, ASCs were applied in an in vivo model of tissue repair to evaluate their regenerative potential.

Results

SAL specimens provided significantly fewer ASCs when compared to excised fat tissue, however, with equivalent viability. SAL-derived ASCs demonstrated greater expression of the adipogenic markers FABP-4 and LPL, although this did not result in a difference in adipogenic differentiation. There were no differences detected in osteogenic differentiation capacity as measured by alkaline phosphatase, mineralization or osteogenic gene expression. Both SAL- and resection-derived ASCs enhanced significantly cutaneous healing and vascularization in vivo, with no significant difference between the two groups.

Conclusion

SAL provides viable ASCs with full capacity for multi-lineage differentiation and tissue regeneration, and is an effective method of obtaining ASCs for cell-based therapies.