Cell-assisted lipotransfer: Current concepts

Outcomes of Autologous Fat Graft Injection(s) in Treating Sequelae of Digital Trauma: A Case Series

Background: Sequelae of digital trauma, such as painful scars adherent to tendons and bones, pain of neural origin, cold intolerance, skin and pulp atrophy, occur frequently. Autologous fat graft injections is an interesting option to treat these sequelae. The aim of this study is to describe the outcomes of autologous fat graft injections to treat sequelae of digital trauma. Methods: This retrospective study included all adult patients with digital trauma who underwent an autologous fat grafting procedure at our hospital between 2015 and 2019. The procedure was done at least 6 months after the initial trauma. Outcomes were assessed at least 9 months after the injection and included 2-point epicritic discrimination by Weber test (2-PD) and pulp circumference of the affected finger compared with the contralateral finger, a satisfaction questionnaire concerning the improvement of symptoms, aesthetic aspects and pain related to the operation, evaluation of pain by visual analogue scale, quality of life by SF-36 score and quick disabilities of the arm, shoulder and hand questionnaire (QuickDASH) score. We also assessed whether the patients had reintegrated a previously excluded finger. Results: The study included 14 patients. All patients received one session except for one patient who received two sessions. The average 2-PD of the injured finger was 7 mm compared to 3.57 mm for the contralateral finger. There was no difference in pulp circumference between the treated and contralateral fingers. The mean satisfaction score for symptom improvement and aesthetic improvement was 3.36/5, and the mean score for procedure-related pain was 2.36/5. The mean VAS of the patients was 2.91/10, the mean SF-36 was 60.42/100 and the mean QuickDASH was 40.09/100. Five of the nine patients who had a previously excluded finger were able to reintegrate it. Conclusions: Autologous fat transfer seems to offer some benefit in patients with adherent scars and pulp atrophy. It has little effect on neuropathic pain. Level of Evidence: Level IV (Therapeutic).

Exosomes Derived from Human Adipose-Derived Stem Cells Cannot Distinctively Promote Graft Survival in Cryopreservation Fat Grafting

BACKGROUND

Cryopreserved fat has limited clinical applications due to its rapid absorption, high degree of fibrosis, and risk of complications after grafting. Many studies have verified that Adipose-derived mesenchymal stem cell-derived exosomes (ADSC-Exos) can improve fresh fat graft survival. This study assessed whether ADSC-Exos could improve the survival of cryopreserved fat grafts.

METHODS

Exosomes were isolated from human ADSCs were subcutaneously engrafted with adipose tissues stored under different conditions (fresh; cryopreserved for 1 month) into the backs of BALB/c nude mice (n = 24), and exosomes or PBS were administered weekly. Grafts were harvested at 1, 2, 4, and 8 weeks, and fat retention rate, histologic, and immunohistochemical analyses were conducted.

RESULTS

At 1, 2, and 4 weeks after the transfer, cryopreserved fat grafts in groups of exosome-treated showed better fat integrity, fewer oil cysts, and reduced fibrosis. Further investigations of macrophage infiltration and neovascularization revealed that those exosomes increased the number of M2 macrophages at 2 and 4 weeks (p<0.05), but had limited impact on vascularization (p>0.05). It's important to note that no significant differences (p>0.05) were observed between the two groups in both histological and immunohistochemical evaluations at 8 weeks post-transplantation.

CONCLUSIONS

This study suggests that ADSC-Exos could improve the survival of cryopreserved fat grafts in the short term (within 4 weeks), but the overall improvement was poor (after 8 weeks). This suggests that the utility of using ADSC-Exos to treat cryopreserved adipose tissue grafts is limited.

NO LEVEL ASSIGNED

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Concentrated ultrasound-processed fat (CUPF): More than a mechanically emulsified graft

INTRODUCTION

Autologous fat grafting is still an evolving technique. Researchers have attempted to increase the survival rate of grafts by concentrating adipose-derived stem cells (ASCs). In this study, we investigate a novel method that combines ultrasonic processing and centrifugation to generate small fat particles termed concentrated ultrasound-processed fat (CUPF) for grafting.

METHODS

The standard approach for obtaining CUPF is described. The properties of processed fat, including CUPF, microfat, centrifuged fat, and nanofat, were investigated using histological observation. Comparative analyses were conducted on the cell number, viability, and immunophenotypic profile of stromal vascular fraction cells (SVFs). Cultured ASCs were evaluated for cell proliferation and adipogenic, osteogenic, and chondrogenic potential. The processed fats were transplanted and evaluated using in vivo and histological studies.

RESULTS

Compared with microfat, centrifuged fat, and nanofat, CUPF had a condensed tissue content and higher concentration of viable cells in a small tissue structure and could smoothly pass through a 27-gauge cannula. In the CUPF group, SVFs were isolated in great numbers, with high viability and a high proportion of CD29- and CD105-positive cells. ASCs from the CUPF group exhibited high proliferation and multilineage differentiation potential. The grafts from the CUPF group were well preserved, and histological quantification revealed an increase in the abundance of Ki67- and CD31-positive cells in the tissue.

CONCLUSIONS

Our study established a new fat processing strategy that combines ultrasonic processing and centrifugation to harvest small particle grafts named CUPF. CUPF concentrated a large number of ASCs and has great potential for regenerative therapy.

Mechanical Stress Improves Fat Graft Survival by Promoting Adipose-Derived Stem Cells Proliferation

Cell-assisted lipotransfer (CAL), defined as co-transplantation of aspirated fat with enrichment of adipose-derived stem cells (ASCs), is a novel technique for cosmetic and reconstructive surgery to overcome the low survival rate of traditional fat grafting. However, clinically approved techniques for increasing the potency of ASCs in CAL have not been developed yet. As a more clinically applicable method, we used mechanical stress to reinforce the potency of ASCs. Mechanical stress was applied to the inguinal fat pad by needling. Morphological and cellular changes in adipose tissues were examined by flow cytometric analysis 1, 3, 5, and 7 days after the procedure. The proliferation and adipogenesis potencies of ASCs were evaluated. CAL with ASCs treated with mechanical stress or sham control were performed, and engraftment was determined at 4 weeks post-operation. Flow cytometry analysis revealed that mechanical stress significantly increased the number as well as the frequency of ASC proliferation in fat. Proliferation assays and adipocyte-specific marker gene analysis revealed that mechanical stress promoted proliferation potential but did not affect the differentiation capacity of ASCs. Moreover, CAL with cells derived from mechanical stress-treated fat increased the engraftment. Our results indicate that mechanical stress may be a simple method for improving the efficacy of CAL by enhancing the proliferation potency of ASCs.

Inhibition of RIP3 increased ADSC viability under OGD and modified the competency of adipogenesis, angiogenesis, and inflammation regulation

Adipose-derived stem cells (ADSCs) showed decreased cell viability and increased cell death under oxygen-glucose deprivation (OGD). Meanwhile, vital necroptotic proteins, including receptor-interacting protein kinase (RIP) 3 (RIP3) and mixed lineage kinase domain-like pseudokinase (MLKL), were expressed in the early stage. The present study aims to explore the effect of necroptosis inhibition on ADSCs. ADSCs were obtained from normal human subcutaneous fat and verified by multidirectional differentiation and flow cytometry. By applying cell counting kit-8 (CCK-8), calcein/propidium iodide (PI) staining and immunostaining, we determined the OGD treatment time of 4 h, a timepoint when the cells showed a significant decrease in viability and increased protein expression of RIP3, phosphorylated RIP3 (pRIP3) and phosphorylated MLKL (pMLKL). After pretreatment with the inhibitor of RIP3, necroptotic protein expression decreased under OGD conditions, and cell necrosis decreased. Transwell assays proved that cell migration ability was retained. Furthermore, the expression of the adipogenic transcription factor peroxisome proliferator-activated receptor γ (PPARγ) and quantitative analysis of Oil Red O staining increased in the inhibitor group. The expression of vascular endothelial growth factor-A (VEGFA) and fibroblast growth factor 2 (FGF2) and the migration test suggest that OGD increases the secretion of vascular factors, promotes the migration of human umbilical vein endothelial cells (HUVECs), and forms unstable neovascularization. ELISA revealed that inhibition of RIP3 increased the secretion of the anti-inflammatory factor, interleukin (IL)-10 (IL-10) and reduced the expression of the proinflammatory factor IL-1β. Inhibition of RIP3 can reduce the death of ADSCs, retain their migration ability and adipogenic differentiation potential, reduce unstable neovascularization and inhibit the inflammatory response.

Cell-Assisted Lipotransfer in Breast Augmentation Surgery: Clinical Outcomes and Considerations for Future Research

Autologous fat transfer is a widely used surgical technique, chosen by numerous plastic surgeons for breast augmentation surgery. This technique is based on three steps: 1. harvesting of the lipoaspirate from the patient, 2. centrifugation and removal of the top, oily, layer, and 3. implantation in the patient’s breast(s). It has been associated with various complications, including post-surgical fat resorption, as measured quantitatively with MRI, CT, and other 3D-quantification systems.

Adipose-derived stem cells have been explored as a means of addressing fat resorption. They can be separated from the lipoaspirate following centrifugation, and enzymatically purified from unwanted debris, with collagenase, forming the stromal vascular fraction. The stromal vascular fraction is then recombined with the graft volume prior to implantation. This novel technique, referred to as “cell-assisted lipotransfer”, has shown promising results in terms of reducing fat resorption. These results are due to the pro-angiogenic and pro-adipogenic ability of the stem cells, which allow the graft to address the conditions of ischemia more effectively than autologous fat transfer.

The aim of this review is to explore the ways in which cell-assisted lipotransfer is different from the autologous fat transfer, as well as how and why adipose-derived stem cells may contribute towards limiting fat resorption. The immunological background of these cells is discussed in detail, while grounds for further development are discussed, by means of the administration of external growth factors, which could, potentially, maximize outcomes, while limiting complications.

Clinical Efficacy Analysis of Augmentation Mammoplasty with Cell-Assisted Autologous Fat Transplantation

OBJECTIVE

To analyze the clinical efficacy of augmentation mammoplasty with cell-assisted autologous fat transplantation.

METHODS

Thirty-four cases of micromastia patients in our hospital were randomly divided into control group (n = 17) and observation group (n = 17). Breast augmentation with autologous fat transplantation alone and cell-assisted autologous fat transplantation were performed, respectively, compare and observe the therapeutic effect.

RESULTS

Compared with the control group, the effective rate of breast augmentation was higher in the observation group. After six months of treatment, the increase value of chest circumference (CC), Sternal notch-nipple distance (SN-N),distance between nipple and inframammary fold (N-MF) was higher in the observation group, and the uplift value was higher after six months surgery, with statistical significance (p < 0.05). MRI showed higher postoperative fat retention rate, QLQ-30 Quality of life scores showed no significant difference (p > 0.05).

LEVEL OF EVIDENCE IV

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The Efficacy of Cell-Assisted Lipotransfer Versus Conventional Lipotransfer in Breast Augmentation: A Systematic Review and Meta-Analysis

BACKGROUND

Cell-assisted lipotransfer (CAL) is novel and controversial technique for breast augmentation.

OBJECTIVE

This review and meta-analysis aimed to assess the clinical efficacy of CAL as compared with conventional lipotransfer.

METHODS

PubMed databases were searched with no restrictions for randomized controlled trials (RCTs) and observational studies with control groups. Keywords included "fat graft," "lipotransfer," "lipofilling," "autologous fat," "fat transplantation," "stromal vascular fraction (SVF)," "stem cell," "adipose tissue-derived stromal cell (ADSC)," "adipose tissue-derived stromal cell (ASC)," "called adipose derived progenitor cells (ADRC)," "cell-assisted," "progenitor-enriched," "cell-enhanced" and "breast." Review Manager software (RevMan, version 5.3) was used to compute the pooled effect estimates for fat survival rate and complication rates. Outcomes were expressed as standard mean differences (SMDs) or odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses were performed based on different methods of cell-enhanced fat preparation.

RESULTS

Six studies were included (n_total = 353 adult patients). The fat survival rate was significantly higher in the CAL group than in the control group (SMD = 1.79, 95% CI = 0.28, 3.31; P = 0.02). There were no significant differences in complication rates between the CAL group and the control group (OR = 1.34, 95% CI = 0.65, 2.73; P = 0.43). Subgroup analyses found no significant differences between the SVF and control groups in fat survival rate (SMD = 1.52, 95% CI = -0.21, 3.24; P = 0.08) among both manual and automatic subgroups (P = 0.28 and P = 0.10, respectively). The data analysis showed a significant heterogeneity between manual and automatic subgroups (I² = 57.0%, P = 0.15).

CONCLUSION

This study suggests that cell-assisted lipotransfer is superior to conventional lipotransfer for improved fat survival rate in breast augmentation. However, analyses comparing the SVF-enhanced fat graft with the conventional fat graft noted no differences in fat survival rate. It is necessary to determine which protocol is most beneficial for patients, establish standardized methods of SVF isolation or adipose tissue-derived stromal cells (ADSCs) culture, and a constant percentage of injected cells in the graft. The long-term efficacy and safety of CAL should also be evaluated in further studies, and additional RCTs with larger sample sizes and better comparability 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.

Effect of Co-transplanting Stromal Vascular Fraction-Gelatin and Platelet-Rich Fibrin on the Long-Term Maintenance of Fat Volume

OBJECTIVE

In the present study, we aimed to investigate the survival of stromal vascular fraction-gelatin (SVF-gel) grafts and determine whether co-transplantation of SVF-gel and platelet-rich fibrin (PRF) improves long-term maintenance of fat volume (Wei et al. in Oncotarget 8:68542-68556, 2017) in a rabbit model.

METHODS

SVF-gel was transplanted into the ears of 12 rabbits with (experimental group) or without PRF (control group). Transplantation retention was evaluated based on weight, histology, and immunohistochemistry.

RESULTS

In the 2nd and 4th weeks, the volume of fat was larger in the experimental group than in the control group. In the 6th week, the absorption of fat was noticeable in both groups, and there was no significant difference in the fat survival rate between the two groups (experimental group: 1.051 ± 0.144 and control group: 0.789 ± 0.232, P > 0.05). HE staining results: At week 2, adipocytes were observed in the experimental group and tended to mature over time. These adipocytes also exhibited an ordered arrangement. Adipocytes with abnormal morphology appeared in the control group in the 4th week. At different weeks, there were more inflammatory cells and fibroblasts in the experimental group than in the control group, and they were arranged in an ordered fashion. Immunohistochemical results: More brown areas were observed in the experimental group than in the control group, and the morphology and distribution of adipocytes in the experimental group were better than those in the control group. The distribution of fibrocytes was also more regular in the experimental group than in the control group.

CONCLUSION

SVF-gel cannot maintain long-term filling in rabbit ears. The addition of PRF has no influence, although PRF can induce SVF-gel to transform into adipocytes, and the anti-inflammatory effect is noticeable in the early period following the procedure. Co-transplantation also helped to ensure orderly arrangement of fibrin. There were no "volume preservation differences in this experimental model" perhaps there are differences if other models/methodology are employed. No Level Assigned This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine Ratings, please refer to Table of Contents or online Instructions to Authors - www.springer.com/00266 .

Water jet-assisted lipoaspiration and Sepax cell separation system for the isolation of adipose stem cells with high adipogenic potential

INTRODUCTION

Water jet-assisted liposuction has gained popularity due to favourable fat grafting outcomes. In this study, we compared stem cells obtained from fat isolated with manual or the water jet-assisted procedure.

METHODS

Liposuction of abdominal fat was performed using the two methods on each donor (n = 10). Aspirate samples were collagenase digested and the isolated cells seeded in vitro prior to proliferation, adipogenic differentiation and angiogenic activity analyses.

RESULTS

Cells from either procedure proliferated at similar rates and exhibited a similar colony-forming ability. The cells expressed stem cell markers CD73, CD90 and CD105. In the water jet cell preparations, there were higher numbers of cells expressing CD146. Robust adipogenic differentiation was observed in cultures expanded from both manual and water jet lipoaspirates. Gene analysis showed higher expression of the adipocyte markers aP2 and GLUT4 in the adipocyte-differentiated water jet cell preparations, and ELISA indicated increased secretion of adiponectin from these cells. Both cell groups expressed vasculogenic factors and the water jet cells promoted the highest levels of in vitro angiogenesis. Given these positive results, we further characterised the water jet cells when prepared using an automated closed cell processing unit, the Sepax-2 system (Cytiva). The growth and stem cell properties of the Sepax-processed cells were similar to the standard centrifugation protocol, but there was evidence for greater adipogenic differentiation in the Sepax-processed cells.

CONCLUSIONS

Water jet lipoaspirates yield cells with high adipogenic potential and angiogenic activity, which may be beneficial for use in cell-assisted lipotransfers.

Correction of the Tear Trough Deformity and Concomitant Infraorbital Hollows With Extracellular Matrix/Stromal Vascular Fraction Gel

BACKGROUND

The tear trough deformity is a sign of eye aging. Filling is an ideal choice for the tear trough accompanied by infraorbital hollows.

OBJECTIVE

To evaluate the efficacy and safety of stromal vascular fraction gel (SVF-gel) as a filler for the tear trough deformity which is combined with infraorbital hollows.

MATERIALS AND METHODS

From July 2017 to June 2018, 33 patients underwent autologous fat aspiration and were followed up successfully. Stromal vascular fraction gel was used to correct patients with bilateral Barton I/II; tear trough deformity and infraorbital hollows. Improvement was evaluated by measuring skin-periosteal depth, 3D volume, global aesthetic improvement scale (GAIS), and patient self-assessment.

RESULTS

Skin-periosteal depth improved significantly (p < .001). The volumetric increment of the tear trough and infraorbital regions increased 2.132 ± 0.671 mL, and the retention rate was excellent (72.87 ± 10.23%). The GAIS showed a high score (2.5 ± 0.5 points), with patient self-assessment showing satisfactory results for all 7 questions on the questionnaire.

CONCLUSION

The high retention rate of SVF-gel suggests that it can provide an effective solution to tear trough deformity accompanied by infraorbital hollows.

Adipose tissue-derived stem cells in breast reconstruction: a brief review on biology and translation

Recent developments in adipose-derived stromal/stem cell (ADSC) biology provide new hopes for tissue engineering and regeneration medicine. Due to their pluripotent activity, paracrine activity, and immunomodulatory function, ADSCs have been widely administrated and exhibited significant therapeutic effects in the treatment for autoimmune disorders, neurodegenerative diseases, and ischemic conditions both in animals and human clinical trials. Cell-assisted lipotransfer (CAL) based on ADSCs has emerged as a promising cell therapy technology and significantly improved the fat graft retention. Initially applied for cosmetic breast and facial enhancement, CAL has found a potential use for breast reconstruction in breast cancer patients. However, more challenges emerge related to CAL including lack of a standardized surgical procedure, the controversy in the effectiveness of CAL, and the potential oncogenic risk of ADSCs in cancer patients. In this review, we summarized the latest research and intended to give an outline involving the biological characteristics of ADSCs as well as the preclinical and clinical application of ADSCs.

A novel method for processing adipose-derived stromal stem cells using a closed cell washing concentration device with a hollow fiber membrane module

Cell-assisted lipotransfer (CAL) is an advanced lipoinjection method that uses autologous lipotransfer with addition of a stromal vascular fraction (SVF) containing adipose-derived stromal stem cells (ASCs). The CAL procedure of manual isolation of cells from fat requires cell processing to be performed in clean environment. To isolate cells from fat without the need for a cell processing center, such as in a procedure in an operation theater, we developed a novel method for processing SVF using a closed cell washing concentration device (CCD) with a hollow fiber membrane module. The CCD consists of a sterilized closed circuit, bags and hollow fiber, semi-automatic device and the device allows removal of >99.97% of collagenase from SVF while maintaining sterility. The number of nucleated cells, ASCs and viability in SVF processed by this method were equivalent to those in SVF processed using conventional manual isolation. Our results suggest that the CCD system is as reliable as manual isolation and may also be useful for CAL. This approach will help in the development of regenerative medicine at clinics without a cell processing center.

Adipose-Derived Mesenchymal Stromal Cells in Regenerative Medicine: State of Play, Current Clinical Trials, and Future Prospects

Significance: Wound healing is a complex process involving pain and inflammation, where innervation plays a central role. Managing wound healing and pain remains an important issue, especially in pathologies such as excessive scarring (often leading to fibrosis) or deficient healing, leading to chronic wounds. Recent Advances: Advances in therapies using mesenchymal stromal cells offer new insights for treating indications that previously lacked options. Adipose-derived mesenchymal stromal cells (AD-MSCs) are now being used to a much greater extent in clinical trials for regenerative medicine. However, to be really valid, these randomized trials must imperatively follow strict guidelines such as consolidated standards of reporting trials (CONSORT) statement. Indeed, AD-MSCs, because of their paracrine activities and multipotency, have potential to cure degenerative and/or inflammatory diseases. Combined with their relatively easy access (from adipose tissue) and proliferation capacity, AD-MSCs represent an excellent candidate for allogeneic treatments. Critical Issues: The success of AD-MSC therapy may depend on the robustness of the biological functions of AD-MSCs, which requires controlling source heterogeneity and production processes, and development of biomarkers that predict desired responses. Several studies have investigated the effect of AD-MSCs on innervation, wound repair, or pain management separately, but systematic evaluation of how those effects could be combined is lacking. Future Directions: Future studies that explore how AD-MSC therapy can be used to treat difficult-to-heal wounds, underlining the need to thoroughly characterize the cells used, and standardization of preparation processes are needed. Finally, how this a priori easy-to-use cell therapy treatment fits into clinical management of pain, improvement of tissue healing, and patient quality of life, all need to be explored.

Advances in regenerative therapy: A review of the literature and future directions

There is enormous global anticipation for stem cell-based therapies that are safe and effective. Numerous pre-clinical studies present encouraging results on the therapeutic potential of different cell types including tissue derived stem cells. Emerging evidences in different fields of research suggest several cell types are safe, whereas their therapeutic application and effectiveness remain challenged. Multiple factors that influence treatment outcomes are proposed including immunocompatibility and potency, owing to variations in tissue origin, ex-vivo methodologies for preparation and handling of the cells. This communication gives an overview of literature data on the different types of cells that are potentially promising for regenerative therapy. As a case in point, the recent trends in research and development of the mesenchymal stem cells (MSCs) for cell therapy are considered in detail. MSCs can be isolated from a variety of tissues and organs in the human body including bone marrow, adipose, synovium, and perinatal tissues. However, MSC products from the different tissue sources exhibit unique or varied levels of regenerative abilities. The review finally focuses on adipose tissue-derived MSCs (ASCs), with the unique properties such as easier accessibility and abundance, excellent proliferation and differentiation capacities, low immunogenicity, immunomodulatory and many other trophic properties. The suitability and application of the ASCs, and strategies to improve the innate regenerative capacities of stem cells in general are highlighted among others.

Extracellular vesicles derived from human adipose-derived stem cells promote the exogenous angiogenesis of fat grafts via the let-7/AGO1/VEGF signalling pathway

Extracellular vesicles (EVs) derived from human adipose-derived stem cells (hADSCs) possess the proangiogenic potential for ischaemic diseases. Thus, our study aimed to evaluate the therapeutic effects of hADSC-EVs on fat grafting and explore the mechanism of hADSC-EVs promoting angiogenesis. The EVs released by hADSCs incubated under normal or hypoxic conditions were employed to supplement fat grafting in a nude mouse model. The proliferation, migration, tube formation and vascular endothelial growth factor (VEGF) secretion of vascular endothelial cells co-cultured with two kinds of hADSC-EVs were analysed. MicroRNA sequencing was performed to reveal the species and content of microRNAs in hADSC-EVs, the key microRNAs were blocked, and their effect in promoting angiogenesis was detected via above protocols as a reverse proof. The results demonstrate that hADSC-EVs could improve the survival of fat grafts by promoting exogenous angiogenesis and enhance the proliferation, migration, tube formation and VEGF secretion of vascular endothelial cells. In addition, the pro-angiogenic effect of hADSC-EVs in vivo and vitro could be enhanced by hypoxic pre-treatment. We found that the let-7 family, a kind of hypoxic-related microRNA, is enriched in hypoxic hADSC-EVs that contribute to angiogenesis via the let-7/argonaute 1 (AGO1)/VEGF signalling pathway.

Exosomes Are Comparable to Source Adipose Stem Cells in Fat Graft Retention with Up-Regulating Early Inflammation and Angiogenesis

BACKGROUND

Exosomes derived from mesenchymal stem cells possess functional properties similar to those of their parent cells, suggesting that they could play a pivotal role in tissue repair and regeneration.

METHODS

Using lipotransfer as a surrogate, exosomes were isolated from mouse adipose-derived stem cell-conditioned medium and characterized. Minced fat tissue mixed with exosomes, source cells (cell-assisted lipotransfer), or saline was implanted subcutaneously in the lower back of C57/BL mice bilaterally (n = 16 each). Transferred fat tissues were harvested and analyzed at 3 and 10 weeks.

RESULTS

At 3 and 10 weeks after the transfer, fat grafts in groups of exosomes and cell-assisted lipotransfer showed better fat integrity, fewer oil cysts, and reduced fibrosis. At week 10, graft retention rates in cell-assisted lipotransfer (50.9 ± 2.4 percent; p = 0.03) and exosome groups (56.4 ± 1.6 percent; p < 0.001) were significantly higher than in the saline group (40.7 ± 4.7 percent). Further investigations of macrophage infiltration, inflammatory factors, angiogenic factors, adipogenic factors, and extracellular matrix revealed that those exosomes promoted angiogenesis and up-regulated early inflammation, whereas during mid to late stages of fat grafting, they exerted a proadipogenic effect and also increased collagen synthesis level similarly to their source cells.

CONCLUSIONS

The adipose-derived stem cell-derived exosomes demonstrated effects comparable to those of their source cells in achieving improved graft retention by up-regulating early inflammation and augmenting angiogenesis. These features may enable exosomes to be an attractive cell-free alternative in therapeutic regenerative medicine.

The Effect of Early Rounds of ex vivo Expansion and Cryopreservation on the Adipogenic Differentiation Capacity of Adipose-Derived Stromal/Stem Cells

Multipotent adipose-derived stromal/stem cells (ASCs) are candidates for use in cellular therapies for the treatment of a variety of conditions/diseases. Ex vivo expansion of freshly isolated ASCs may be necessary prior to clinical application to ensure that clinically relevant cell numbers are administered during treatment. In addition, cryopreserving cells at early passages allows for storage of freshly isolated cells for extended periods of time before expanding these cells for clinical usage. There are however several concerns that these laboratory-based procedures may alter the characteristics of the cells and in so doing decrease their regenerative potential. In this study we report on the impact of early rounds of cryopreservation (P0) and ex vivo expansion (P0 to P5) on the phenotypic characteristics and adipogenic differentiation potential of ASCs. Our results show that ASCs that upregulate CD36 expression during adipogenic differentiation gradually decrease with increasing expansion rounds. The consequent decrease in adipogenic differentiation capacity was evident in both gene expression and flow cytometry-based phenotypic studies. Successive rounds of expansion did not however alter cell surface marker expression of the cells. We also show that early cryopreservation of ASCs (at P0) does not affect the adipogenic differentiation potential of the cells.

Synergistic Effect of Adipose-Derived Stem Cells and Fat Graft on Wrinkles in Aged Mice

BACKGROUND

The authors investigated the synergistic effects of adipose-derived stem cells and fat graft on skin wrinkles in a nude mouse model of chronologic aging.

METHODS

After 50 weeks of chronologic aging, 44 female BALB/c nude mice were classified into four groups: (1) negative control, (2) mice injected subcutaneously with fat on the back skin (0.5 cm), (3) mice injected with adipose-derived stem cells (1 × 10 cells in 0.5 cm Hanks balanced salt solution), and (4) mice injected with both fat (0.5 cm) and adipose-derived stem cells (1 × 10 cells in 0.5 cm Hanks balanced salt solution). The degree of wrinkling was evaluated using replica analysis, and skin biopsies were performed after 4 weeks. The dermal thickness and density of collagen were determined. Type I procollagen and matrix metalloproteinase levels were determined using real-time polymerase chain reaction and Western blot analysis. Tropoelastin, fibrillin-1, and CD31 levels were evaluated using immunohistochemistry.

RESULTS

Based on the total wrinkle area, there was significant wrinkle reduction in the fat-treated and adipose-derived stem cell with fat-treated groups. Type I procollagen mRNA and collagen levels were significantly higher in the adipose-derived stem cell with fat-treated group than in the adipose-derived stem cell-treated and the fat-treated groups. In addition, the adipose-derived stem cells with fat graft group exhibited significantly higher CD31 expression level than the adipose-derived stem cell-treated and the fat-treated groups.

CONCLUSION

Both adipose-derived stem cells and fat graft have a wrinkle-reducing effect and synergistically affect collagen synthesis and neovascularization.

Mechanical process prior to cryopreservation of lipoaspirates maintains extracellular matrix integrity and cell viability: evaluation of the retention and regenerative potential of cryopreserved fat-derived product after fat grafting

Background

Cryopreservation of fat grafts facilitates reinjection for later use. However, low temperature and thawing can disrupt tissues and cause lipid leakage, which raises safety concerns. Here, we compared the cryopreservation potential of stromal vascular fraction (SVF) gel processed from lipoaspirate with that of fat.

Methods

Human SVF gel and fat were cryopreserved at − 20 °C without cryoprotectant for 1 month. Fresh SVF gel and fat were used as controls. Tissue viability, adipose-derived stem cell (ASC) function, and the extracellular content were evaluated. At 3 months after transplanting the specimens to immunocompromised mice subcutaneously, the grafts were examined for retention, tissue engraftment, and inflammatory levels. The regenerative effect of cryopreserved SVF gel was evaluated in a murine ischemic wound healing model.

Results

At 1 month, the cell death rate in the SVF gel group was 36 ± 2%. The survived ASCs not only could be isolated via explant culture but also preserved colony-forming and differentiation. However, prolonged cryopreservation exacerbated apoptosis. Assessment of recovered tissues showed that the morphology, cell viability, and extracellular protein enrichment were better in SVF gel-preserved tissues than in frozen fat. At 3 months after lipotransfer, the retention ability of 1-month cryopreserved fat was 41.1 ± 9% compared to that of 1-month cryopreserved SVF gel. Immunostaining results showed that adipose tissue regeneration and integrity in the 1-month cryopreserved SVF gel group were superior to those of the cryopreserved fat group. The cryopreserved SVF gel also accelerated healing of the ischemic wound, compared with cryopreserved fat.

Conclusion

Cryopreserved SVF gel maintained tissue integrity and cell viability and resulted in a better long-term retention rate than that of cryopreserved fat. Cryopreserved SVF gel also showed superior regenerative potential and improved ischemic wound healing.

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.

Perspectives for Clinical Translation of Adipose Stromal/Stem Cells

Adipose stromal/stem cells (ASCs) are an ideal cell type for regenerative medicine applications, as they can easily be harvested from adipose tissue in large quantities. ASCs have excellent proliferation, differentiation, and immunoregulatory capacities that have been demonstrated in numerous studies. Great interest and investment have been placed in efforts to exploit the allogeneic use and immunomodulatory and anti-inflammatory effects of ASCs. However, bridging the gap between in vitro and in vivo studies and moving into clinical practice remain a challenge. For the clinical translation of ASCs, several issues must be considered, including how to characterise such a heterogenic cell population and how to ensure their safety and efficacy. This review explores the different phases of in vitro and preclinical ASC characterisation and describes the development of appropriate potency assays. In addition, good manufacturing practice requirements are discussed, and cell-based medicinal products holding marketing authorisation in the European Union are reviewed. Moreover, the current status of clinical trials applying ASCs and the patent landscape in the field of ASC research are presented. Overall, this review highlights the applicability of ASCs for clinical cell therapies and discusses their potential.

Adipose Stromal Vascular Fraction Gel Grafting: A New Method for Tissue Volumization and Rejuvenation

BACKGROUND

The clinical outcomes of fat grafting vary and are technique-dependent. Stromal vascular fraction (SVF) gel is a novel, mechanically processed fat product with high concentrations of adipose tissue-derived stem cells and other SVF cells. This study evaluated the volumization and rejuvenation effects of SVF-gel.

OBJECTIVE

This study evaluated the volumization and rejuvenation effects of SVF-gel.

METHODS

This retrospective, single-center study included 126 patients who underwent SVF-gel grafting and 78 who underwent conventional lipoinjection for various indications from March 2015 to February 2017. Patient satisfaction and secondary surgery rates were evaluated. Samples of transferred SVF-gel were harvested and examined histologically.

RESULTS

All patients showed improvements in facial augmentation and contour. Patients in the SVF-gel group experienced mild postoperative swelling and a low secondary surgery rate (10.9%). Assessment of patient-rated satisfaction on a 5-point Likert scale found that 77.3% of patients in the SVF-gel group were satisfied (54.5%) or very satisfied (22.8%) with their outcomes. By comparison, 53.8% of patients who underwent conventional lipoinjection were satisfied (48.7%) or very satisfied (5.1%). Moreover, SVF-gel showed effective antiwrinkle and skin rejuvenation effects. Hematoxylin-eosin staining showed a normal adipose tissue structure in transferred SVF-gel.

CONCLUSION

Stromal vascular fraction gel is effective for both volumization and rejuvenation, and may be superior to conventional lipoinjection for facial recontouring.

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.

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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.

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

Co-Transplantation of Nanofat Enhances Neovascularization and Fat Graft Survival in Nude Mice

BACKGROUND

Autologous fat grafting is commonly used for soft-tissue augmentation and reconstruction. However, this technique is limited by a high rate of graft absorption. Thus, approaches to improve fat graft survival that promote neovascularization are of great interest. Nanofat has several beneficial features that may render it more suitable for clinical applications than other stem-cell based approaches.

OBJECTIVES

We aimed to determine whether nanofat could enhance new vessel formation and improve the long-term retention of fat grafts.

METHODS

Nanofat was processed via mechanical emulsification and filtration. Fat grafts were transplanted subcutaneously under the scalps of nude mice with different nanofat volumes or without nanofat. The grafted fat was dissected 12 weeks after transplantation. Graft weight and volume were measured, and histological evaluations, including capillary density measurement, were performed.

RESULTS

The co-transplantation of fat with nanofat showed higher graft weight and volume retention, better histological structure, and higher capillary density compared to that in controls. However, there were no significant differences between the two nanofat volumes utilized.

CONCLUSIONS

Nanofat can enhance neovascularization and improve fat graft survival, providing a potential clinically viable approach to fat graft supplementation in plastic and reconstructive surgery.

Safety Analysis of Autologous Stem Cell Therapy in a Variety of Degenerative Diseases and Injuries Using the Stromal Vascular Fraction

BACKGROUND

Stem cells from adipose tissue offer a novel therapy for patients with damaged tissue. Stromal vascular fraction (SVF) injected into patients may reduce inflammation, promote healing, and repair damaged/scarred tissue. SVF can be isolated from fat (adipose) tissue in an outpatient procedure. The SVF population includes mesenchymal stem cells (MSCs), pericytes, endothelial/progenitor cells, fibroblasts and growth factors where the adipocyte (fat cell) population has been removed. Here we describe the use of SVF in the clinic for degenerative diseases in orthopedics, neurological conditions and systemic conditions in 676 patients.

METHODS

This study demonstrated the strong safety profile from a multi-center analysis of SVF injection in treating various diseases. Approximately 60 mL of fat tissue was removed from the abdomen or flanks using a local tumescent liposuction procedure. The fat was separated via centrifuge to isolate the SVF and the cells were delivered intraarticularly, intravenously, intrathecally, or intradiscally directly into the same patient. All subjects were monitored for adverse events.

RESULTS

The procedure demonstrates exceptional patient safety, and the study underscores the safety of autologous stem cell therapy in general. Few adverse events were reported and were overwhelmingly of mild and transient nature, such as the expected soreness at the site of liposuction and occasional headache.

CONCLUSION

The three deaths reported were most likely not related to the treatment but instead to the underlying disease. Our study demonstrates a strong safety profile with low complication rates.