Harvesting human adipose tissue-derived adult stem cells: resection versus liposuction

The Advantages and Shortcomings of Stem Cell Therapy for Enhanced Bone Healing

This review explores the regenerative potential of key progenitor cell types and therapeutic strategies to improve healing of complex fractures and bone defects. We define, summarize, and discuss the differentiation potential of totipotent, pluripotent, and multipotent stem cells, emphasizing the advantages and shortcomings of cell therapy for bone repair and regeneration. The fundamental role of mesenchymal stem cells is highlighted due to their multipotency to differentiate into the key lineage cells including osteoblasts, osteocytes, and chondrocytes, which are crucial for bone formation and remodeling. Hematopoietic stem cells (HSCs) also play a significant role; immune cells such as macrophages and T-cells modulate inflammation and tissue repair. Osteoclasts are multinucleated cells that are important to bone remodeling. Vascular progenitor (VP) cells are critical to oxygen and nutrient supply. The dynamic interplay among these lineages and their microenvironment is essential for effective bone restoration. Therapies involving cells that are more than "minimally manipulated" are controversial and include embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). ESCs, derived from early-stage embryos, possess pluripotent capabilities and have shown promise in preclinical studies for bone healing. iPSCs, reprogrammed from somatic cells, offer personalized medicine applications and can differentiate into various tissue-specific cell lines. Minimally manipulative cell therapy approaches such as the use of bone marrow aspirate concentrate (BMAC), exosomes, and various biomaterials for local delivery are explored for their effectiveness in bone regeneration. BMAC, which contains mostly immune cells but few mesenchymal and VPs, probably improves bone healing by facilitating paracrine-mediated intercellular communication. Exosome isolation harnesses the biological signals and cellular by-products that are a primary source for cell crosstalk and activation. Safe, efficacious, and cost-effective strategies to enhance bone healing using novel cellular therapies are part of a changing paradigm to modulate the inflammatory, repair, and regenerative pathways to achieve earlier more robust tissue healing and improved physical function. Impact Statement Stem cell therapy holds immense potential for bone healing due to its ability to regenerate damaged tissue. Nonmanipulated bone marrow aspirate contains mesenchymal stem cells that promote bone repair and reduce healing time. Induced pluripotent stem cells offer the advantage of creating patient-specific cells that can differentiate into osteoblasts, aiding in bone regeneration. Other delivery methods, such as scaffold-based techniques, enhance stem cell integration and function. Collectively, these approaches can improve treatment outcomes, reduce recovery periods, and advance our understanding of bone healing mechanisms, making them pivotal in orthopedic research and regenerative medicine.

Adipose-Derived Stem Cell Therapy in Spinal Cord Injury

Spinal cord injury (SCI) is a serious condition accompanied by severe adverse events that affect several aspects of the patient's life, such as motor, sensory, and functional impairment. Despite its severe consequences, definitive treatment for these injuries is still missing. Therefore, researchers have focused on developing treatment strategies aimed at ensuring full recovery post-SCI. Accordingly, attention has been drawn toward cellular therapy using mesenchymal stem cells. Considering their wide availability, decreased immunogenicity, wide expansion capacity, and impressive effectiveness in many therapeutic approaches, adipose-derived stem cell (ADSC) injections in SCI cases have been investigated and showed promising results. In this review, SCI pathophysiology and ADSC transplantation benefits are discussed independently, together with SCI animal models and adipose stem cell preparation and application techniques. The mechanisms of healing in an SCI post-ADSC injection, the outcomes of this therapeutic approach, and current clinical trials are also deliberated, in addition to the challenges and future perspectives, aiming to encourage further research in this field.

Donor Sites and Harvesting Techniques Affect miRNA Cargos of Extracellular Vesicles Released by Human Adipose-Derived Mesenchymal Stromal Cells

Osteoarthritis (OA) is a degenerative joint disorder characterized by the progressive deterioration of articular cartilage driven and sustained by catabolic and inflammatory processes that lead to pain and functional impairment. Adipose-derived stem cells (ASCs) have emerged as a promising therapeutic strategy for OA due to their regenerative potential, which mainly relies on the adaptive release of paracrine molecules that are soluble or encapsulated in extracellular vesicles (EVs). The biological effects of EVs specifically depend on their cargo; in particular, microRNAs (miRNAs) can specifically modulate target cell function through gene expression regulation. This study aimed to investigate the impact of collection site (abdominal vs. peri-trochanteric adipose tissue) and collection method (surgical excision vs. lipoaspiration) on the miRNAs profile in ASC-derived EVs and their potential implications for OA therapy. EV-miRNA cargo profiles from ASCs of different origins were compared. An extensive bioinformatics search through experimentally validated and OA-related targets, pathways, and tissues was conducted. Several miRNAs involved in the restoration of cartilage homeostasis and in immunomodulation were identified in all ASC types. However, EV-miRNA expression profiles were affected by both the tissue-harvesting site and procedure, leading to peculiar characteristics for each type. Our results suggest that adipose-tissue-harvesting techniques and the anatomical site of origin influence the therapeutic efficacy of ASC-EVs for tissue-specific regenerative therapies in OA, which warrants further investigation.

Clinical Applications of Adipose-Derived Stem Cell (ADSC) Exosomes in Tissue Regeneration

Adipose-derived stem cells (ADSCs) are mesenchymal stem cells with a great potential for self-renewal and differentiation. Exosomes derived from ADSCs (ADSC-exos) can imitate their functions, carrying cargoes of bioactive molecules that may affect specific cellular targets and signaling processes. Recent evidence has shown that ADSC-exos can mediate tissue regeneration through the regulation of the inflammatory response, enhancement of cell proliferation, and induction of angiogenesis. At the same time, they may promote wound healing as well as the remodeling of the extracellular matrix. In combination with scaffolds, they present the future of cell-free therapies and promising adjuncts to reconstructive surgery with diverse tissue-specific functions and minimal adverse effects. In this review, we address the main characteristics and functional properties of ADSC-exos in tissue regeneration and explore their most recent clinical application in wound healing, musculoskeletal regeneration, dermatology, and plastic surgery as well as in tissue engineering.

A phase I/II clinical trial of ex-vivo expanded human bone marrow derived allogeneic mesenchymal stromal cells in adult patients with perianal fistulizing Crohn's Disease

BACKGROUND

Perianal fistulas (PF) affect one-third patients with Crohn's disease (CD) with limited therapeutic options. There is dearth of literature on safety and efficacy of bone marrow-derived mesenchymal stromal cells (BMSCs) in this population.

METHODS

An open-label, phase I/II, single-arm study was conducted involving local administration of human allogeneic bone marrow-derived mesenchymal stromal cells in perianal fistula of patients with Crohn's disease refractory to standard therapies. Clinical severity and biomarkers were assessed at baseline and periodically until week 104 , and MRI at week 24 and 104. Primary and secondary objectives were to assess safety and efficacy respectively. Fistula remission was complete closure of fistula openings with < 2 cm perianal collection on MRI, and fistula response was decrease in drainage by ≥ 50%. Change in perianal disease activity index, quality-of-life and Van Assche index on MRI over time was assessed using mixed-effect linear regression model.

RESULTS

Ten patients (male:8, mean age:27.4 ± 12.0years) were recruited. Self-resolving procedure-related adverse events occurred in three patients, with no follow-up adverse events. In intention to treat analysis at week 24, two patients (20%) achieved fistula remission and seven (70%) had fistula response. At week 52, two (20%) patients were in remission and seven (70%) maintained response. At 104 weeks, two (20%) patients maintained response and one (10%) was in remission. Statistically significant decrease in perianal disease activity index (P = 0.008), Van Assche Index (P = 0.008) and improvement in quality-of-life (P = 0.001) were observed over time.

CONCLUSIONS

Allogeneic BMSCs are safe and effective for the treatment of perianal fistulizing CD with significant improvement in clinical severity and radiological healing.

TRIAL REGISTRATION

The study was prospectively registered on Clinical trials registry - India (CTRI), CTRI/2020/01/022743 on 14 January 2020, http://ctri.nic.in .

Exosomes from Adipose-Tissue-Derived Stem Cells Induce Proapoptotic Gene Expression in Breast Tumor Cell Line

Lipofilling is an option for breast reconstruction after tumor resection to avoid the complications of an implant-based reconstruction. Although some concerns exist regarding the oncological safety of tissue rich in mesenchymal stem cells with their proangiogenic and proliferation-supportive properties, there are also reports that adipose-tissue-derived stem cells can exhibit antitumoral properties. We isolated primary adipose-tissue-derived stem cells. Both conditioned medium and exosomes were harvested from the cell culture and used to treat the breast cancer cell line MCF-7. Cell viability, cytotoxicity, and gene expression of MCF-7 cells in response to the indirect co-culture were evaluated. MCF-7 cells incubated with exosomes from adipose-tissue-derived stem cells show reduced cell viability in comparison to MCF-7 cells incubated with adipose-tissue-derived stem-cell-conditioned medium. Expression of proapoptotic genes was upregulated, and expression of antiapoptotic genes was downregulated. The debate about the oncological safety of autologous fat grafting after tumor resection continues. Here, we show that exosomes from adipose-tissue-derived stem cells exhibit some antitumoral properties on breast cancer cell line MCF-7.

Effect of Donor Site Selection for Fat Grafting on the Yield and Viability of the Stromal Vascular Fraction

BACKGROUND

The efficacy of stromal vascular fraction (SVF) treatment, or stem cell treatment, directly depends on the SVF cell count and the cells' viability. The SVF cell count and viability are in direct correlation with the adipose tissue harvesting site that yields SVF cells, making this research a contribution to developing tissue guidance.

OBJECTIVES

The aim of this study was to investigate the importance of harvesting subcutaneous adipose tissue-derived SVF cells on the concentration and viability of SVF.

METHODS

Adipose tissue was collected by vibration-assisted liposuction from the regions of the upper and lower abdomen, lumbar region, and inner thigh region. With the semiautomatic UNISTATION 2nd Version system, the obtained fat was chemically processed (with collagenase enzyme) and a concentrate of SVF cells was obtained by centrifugation. These samples were then analyzed with the Luna-Stem Counter device to measure the number and viability of SVF cells.

RESULTS

When comparing the regions of the upper abdomen, lower abdomen, lumbar region, and inner thigh, the highest concentration of SVF was found in the lumbar region, specifically at an average of 97,498.00 per 1.0 mL of concentrate. The lowest concentration was found in the upper abdominal region. When ranking the viability values, the highest cell viability of SVF was observed in the lumbar region, measuring 36.6200%. The lowest viability was found in the upper abdominal region, measuring 24.4967%.

CONCLUSIONS

By comparing the upper and lower abdominal, lumbar, and inner thigh regions, the authors have come to the conclusion that, on average, the largest number of cells with the highest viability was obtained from the lumbar region.

Mesenchymal stem cell-derived exosomes: The dawn of diabetic wound healing

Chronic wound healing has long been an unmet medical need in the field of wound repair, with diabetes being one of the major etiologies. Diabetic chronic wounds (DCWs), especially diabetic foot ulcers, are one of the most threatening chronic complications of diabetes. Although the treatment strategies, drugs, and dressings for DCWs have made great progress, they remain ineffective in some patients with refractory wounds. Stem cell-based therapies have achieved specific efficacy in various fields, with mesenchymal stem cells (MSCs) being the most widely used. Although MSCs have achieved good feedback in preclinical studies and clinical trials in the treatment of cutaneous wounds or other situations, the potential safety concerns associated with allogeneic/autologous stem cells and unknown long-term health effects need further attention and supervision. Recent studies have reported that stem cells mainly exert their trauma repair effects through paracrine secretion, and exosomes play an important role in intercellular communication as their main bioactive component. MSC-derived exosomes (MSC-Exos) inherit the powerful inflammation and immune modulation, angiogenesis, cell proliferation and migration promotion, oxidative stress alleviation, collagen remodeling imbalances regulation of their parental cells, and can avoid the potential risks of direct stem cell transplantation to a large extent, thus demonstrating promising performance as novel "cell-free" therapies in chronic wounds. This review aimed to elucidate the potential mechanism and update the progress of MSC-Exos in DCW healing, thereby providing new therapeutic directions for DCWs that are difficult to be cured using conventional therapy.

Extracellular vesicle and soluble fractions of adipose tissue-derived mesenchymal stem cells secretome induce inflammatory cytokines modulation in an in vitro model of discogenic pain

BACKGROUND CONTEXT

Mesenchymal stem cells (MSCs) secretome or conditioned medium (CM) is a complex cocktail of different molecules, some of which, particularly those contained in extracellular vesicles, already have proven therapeutic applications.

PURPOSE

CM may well represent promising therapy for discogenic pain and the intention of this work is to assess its therapeutic potential using an in vitro model of this condition.

STUDY DESIGN

This is an experimental study.

METHODS

Our in vitro model comprised nucleus pulposus (NP) and annulus fibrosus (AF) cells inflamed with TNF. To assess the potential therapeutic value of CM and its components, extracellular vesicles (EVs) and soluble culture fraction (SF), cell inflammation took place under 3 different conditions: either in the presence of whole CM, isolated EVs or SF, and concentrations of pro-inflammatory cytokines, metalloproteinases (MMPs) and neurotrophic factors produced in all 3 cases were compared.

RESULTS

In the presence of whole CM, both in vitro gene expression by the NP and AF test cells and analysis of their protein content showed high modulatory effects on inflammation and MMP inhibition. The presence of EVs and SF showed similar but much smaller effects, and this was particularly marked in the case of NP cells.

CONCLUSIONS

Our results show that, compared to EVs and SF, the presence of whole CM has the greatest positive effect on the modulation of pro-inflammatory and catabolic factors. These observations suggest that CM could protect against inflammation and the resulting intervertebral disc (IVD) degeneration that leads to discogenic pain.

CLINICAL SIGNIFICANCE

Many patients' expectations are not met by current non-operative and surgical treatments for discogenic low back pain. We propose the use of the MSCs secretome for assessing its potential as cell-free therapy to treat degenerative disc disease modulating the inflammatory response.

A systematic review on the role of MSC-derived exosomal miRNAs in the treatment of heart failure

BACKGROUND

This systematic review summarizes results of studies that evaluated the expression of microRNAs (miRs) in pre-diabetes or type 2 diabetes.

METHODS

The information was obtained in PubMed, EMBL-EBI, Wanfang, Trip Database, Lilacs, CINAHL and Google. A qualitative synthesis of the results was performed and miRs frequency was graphically. From 1880 we identified studies, only 53 fulfilled the inclusion criteria. The 53 studies analyzed miRs in T2D; and of them, thirteen also described data in pre-diabetes.

RESULTS

In diabetics, 122 miRs were reported and 35 miRs for pre-diabetics. However, we identified that 5 miRs (-122-5p, 144-3p, 210, 375, -126b) were reported more often in diabetics, and 4 (144-3p, -192, 29a and -30d) in pre-diabetics.

CONCLUSIONS

Circulating miRs could be used as biomarkers of type 2 diabetes. However, it is necessary to validate these microRNAs in prospective and multi-center studies, where different population subgroups, considering the age, gender, and risk factors.

Does Water-Jet Force Affect Cryopreserved Adipose-Derived Stem Cells? Evidence of Improved Cell Viability and Fat Graft Survival

BACKGROUND

Adipose tissue harvested by liposuctions is an available source of adipose-derived stem cells (ASCs). Water-jet-assisted liposuction is a favorable method for fat collection with little mechanical damage. This study aimed to investigate whether or not the water-jet-assisted liposuction made a difference in the biological characteristics of cryopreserved ASCs and fat graft survival in cell-assisted lipotransfer.

METHODS

Human lipoaspirates were obtained from the abdomen or thighs of 20 female participants for body contouring. A single surgeon randomly harvested 50 mL of adipose tissue by the water-jet-assisted liposuction and the conventional liposuction, respectively. Adipose-derived stem cells were isolated from lipoaspirates and then cryopreserved for 4 weeks. Cryopreserved ASCs were used to examine the surface markers, cell proliferation, migration, and adipogenic differentiation in vitro. The fat survival of ASCs-enriched grafts from different liposuctions was measured in animal models.

RESULTS

The cryopreserved ASCs with the water-jet assistance had better capacities of cell proliferation, migration, and adipogenic differentiation and achieved a better survival result of ASCs-enriched fat grafting.

CONCLUSIONS

Cryopreservation of ASCs with the water-jet force showed more excellent biological characteristics. The water-jet-assisted liposuction was superior to the conventional liposuction in obtaining ASCs and fat survival of coimplantation with grafts.

Novel cell sources for bone regeneration

A plethora of both acute and chronic conditions, including traumatic, degenerative, malignant, or congenital disorders, commonly induce bone disorders often associated with severe persisting pain and limited mobility. Over 1 million surgical procedures involving bone excision, bone grafting, and fracture repair are performed each year in the U.S. alone, resulting in immense levels of public health challenges and corresponding financial burdens. Unfortunately, the innate self-healing capacity of bone is often inadequate for larger defects over a critical size. Moreover, as direct transplantation of committed osteoblasts is hindered by deficient cell availability, limited cell spreading, and poor survivability, an urgent need for novel cell sources for bone regeneration is concurrent. Thanks to the development in stem cell biology and cell reprogramming technology, many multipotent and pluripotent cells that manifest promising osteogenic potential are considered the regenerative remedy for bone defects. Considering these cells' investigation is still in its relative infancy, each of them offers their own particular challenges that must be conquered before the large-scale clinical application.

Adipose Tissue-Derived Stem Cell Yield Depends on Isolation Protocol and Cell Counting Method

In plastic surgery, lipofilling is a frequent procedure. Unsatisfactory vascularization and impaired cell vitality can lead to unpredictable take rates in the fat graft. The proliferation and neovascularization inducing properties of adipose tissue-derived stem cells may contribute to solve this problem. Therefore, the enrichment of fat grafts with stem cells is studied intensively. However, it is difficult to compare these studies because many factors—often not precisely described—are influencing the results. Our study summarizes some factors which influence the cell yield like harvesting, isolation procedure and quantification. Stem cells were isolated after liposuction. Quantification was done using a cell chamber, colony counting, or flow cytometry with changes to one parameter, only, for each comparison. Quantification of cells isolated after liposuction at the same harvesting site from the same patient can vary greatly depending on the details of the isolation protocol and the method of quantification. Cell yield can be influenced strongly by many factors. Therefore, a comparison of different studies should be handled with care.

Isolation and characterization of exosomes from adipose tissue-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are the subject of intense research as they are a potential therapeutic tool for several clinical applications. The new MSCs action models are focused on the use of MSC-derived secretome which contains several growth factors, cytokines, microRNAs, and extracellular vesicles such as exosomes. Exosomes have recently emerged as a component with great potential involved as mediators in cellular communication. The isolation and identification of exosomes has made it possible for them to be used in cell-free therapies. The purposes of this study are: (i) to detect exosomes released into adipose-derived MSC conditioned cell culture medium, (ii) to identify exosome morphology, and (iii) to carry out a complete characterization of said exosomes. Moreover, it is aimed at determining which method for exosome isolation would be best to use. Precipitation has been identified as a highly useful method of exosome isolation since it provides higher efficiency and purity values than other methods. A broad characterization of the exosomes present in the MSC-conditioned medium was also carried out. This work fills a gap in the existing literature on bioactive molecules which have attracted a great deal of interest due to their potential use in cellular therapies.

Mesenchymal stromal/stem cells and their exosomes for restoration of spermatogenesis in non-obstructive azoospermia: a systemic review

Stem cells have been introduced as new promising therapeutic agents in treatment of degenerative diseases because of having high differentiation potential while maintaining the ability to self-replicate and retaining features of their source cells. Among different type of cell therapies, mesenchymal stromal/stem cell (MSC) therapy is being increasingly developed as a new way to treat structural defects that need to be repaired and regenerated. Non-obstructive azoospermia (NOA) is a reproductive disease in men that causes infertility in 10% of infertile men. Based on in vitro studies, MSCs from different tissue sources have been differentiated into germ cells or gamete progenitor cells by simple methods in both male and female. On the other hand, the therapeutic effects of MSCs have been evaluated for the treatment of NOA animal models created by chemical or surgical compounds. The results of these studies confirmed successful allotransplantation or xenotransplantation of MSCs in the seminiferous tubules. As well, it has been reported that exosomes secreted by MSCs are able to induce the process of spermatogenesis in the testes of infertile animal models. Despite numerous advances in the treatment of reproductive diseases in men and women with the help of MSCs or their exosomes, no clinical trial has been terminated on the treatment of NOA. This systematic review attempts to investigate the possibility of MSC therapy for NOA in men.

In Vitro Culture Expansion Shifts the Immune Phenotype of Human Adipose-Derived Mesenchymal Stem Cells

Human mesenchymal stem or stromal cells (hMSCs) are known for their potential in regenerative medicine due to their differentiation abilities, secretion of trophic factors, and regulation of immune responses in damaged tissues. Due to the limited quantity of hMSCs typically isolated from bone marrow, other tissue sources, such as adipose tissue-derived mesenchymal stem cells (hASCs), are considered a promising alternative. However, differences have been observed for hASCs in the context of metabolic characteristics and response to in vitro culture stress compared to bone marrow derived hMSCs (BM-hMSCs). In particular, the relationship between metabolic homeostasis and stem cell functions, especially the immune phenotype and immunomodulation of hASCs, remains unknown. This study thoroughly assessed the changes in metabolism, redox cycles, and immune phenotype of hASCs during in vitro expansion. In contrast to BM-hMSCs, hASCs did not respond to culture stress significantly during expansion as limited cellular senescence was observed. Notably, hASCs exhibited the increased secretion of pro-inflammatory cytokines and the decreased secretion of anti-inflammatory cytokines after extended culture expansion. The NAD+/NADH redox cycle and other metabolic characteristics associated with aging were relatively stable, indicating that hASC functional decline may be regulated through an alternative mechanism rather than NAD+/Sirtuin aging pathways as observed in BM-hMSCs. Furthermore, transcriptome analysis by mRNA-sequencing revealed the upregulation of genes for pro-inflammatory cytokines/chemokines and the downregulation of genes for anti-inflammatory cytokines for hASCs at high passage. Proteomics analysis indicated key pathways (e.g., tRNA charging, EIF2 signaling, protein ubiquitination pathway) that may be associated with the immune phenotype shift of hASCs. Together, this study advances our understanding of the metabolism and senescence of hASCs and may offer vital insights for the biomanufacturing of hASCs for clinical use.

Facial Rejuvenation with Concentrated Lipograft-A 12 Month Follow-Up Study

Lipofilling is a popular technique to treat volume loss in aging patients. The isolated adipose tissue is composed of adipocytes and stromal vascular fraction cells, which include adipose-derived stem cells (ASC). We hypothesize that the patient’s wrinkle severity scale (WSS) and patient’s satisfaction on the global aesthetic improvement scale (GAIS) can be improved after using concentrated lipoaspirate. Fourteen patients (54 years ± 11.09 years) with volume loss in the midface area underwent waterjet-assisted liposuction (Human Med AG, Schwerin, Germany). Fat was centrifuged in an ACP Double Syringe (Arthrex GmbH, Munich, Germany) using Rotofix 32A centrifuge (Andreas Hettich, GmbH & Co.KG, Tuttlingen, Germany). Homogenization was performed using the double syringe and a 1.4 mm female–female luerlock connector. After a second centrifugation, patients received periorbital (PO) and nasolabial (NL) lipografting. ASC count was performed after enzymatical digestion. Vitality of cells was assessed using a resazurin assay. During long-term follow up (12 months, n = 10), we found a high patient’s satisfaction (GAIS 1+/−0.52) and a good improvement of the WSS during short- and long-term follow-up. The ASC count of processed lipoaspirate was 2.1-fold higher than of unprocessed lipoaspirate (p < 0.001). The difference of ASC in sedimented and simply centrifuged lipoaspirate was also significant (p < 0.05). Facial rejuvenation with concentrated fat graft offers good results concerning objective aesthetic outcome and patient’s satisfaction.

Shear Force Processing of Lipoaspirates for Stem Cell Enrichment Does Not Affect Secretome of Human Cells Detected by Mass Spectrometry In Vitro

BACKGROUND

Lipofilling is one of the most often performed surgical procedures in plastic and reconstructive surgery. Lipoaspirates provide a ready source of stem cells and secreted factors that contribute to neoangiogenesis and fat graft survival. However, the regulations about the enrichment of these beneficial cells and factors are ambiguous. In this study, the authors tested whether a combination of centrifugation and homogenization allowed the enrichment of viable stem cells in lipoaspirates through the selective removal of tumescent solution, blood, and released lipids without significantly affecting the cell secretome.

METHODS

Human lipoaspirate was harvested from six different patients using water jet-assisted liposuction. Lipoaspirate was homogenized by first centrifugation (3584 rpm for 2 minutes), shear strain (10 times intersyringe processing), and second centrifugation (3584 rpm for 2 minutes). Stem cell enrichment was shown by cell counting after stem cell isolation. Lipoaspirate from different processing steps (unprocessed, after first centrifugation, after homogenization, after second centrifugation) was incubated in serum-free cell culture medium for mass spectrometric analysis of secreted proteins.

RESULTS

Lipoaspirate homogenization leads to a significant 2.6 ± 1.75-fold enrichment attributable to volume reduction without reducing the viability of the stem cells. Protein composition of the secretome did not change significantly after tissue homogenization. Considering the enrichment effects, there were no significant differences in the protein concentration of the 83 proteins found in all processing steps.

CONCLUSIONS

Stem cells can be enriched mechanically without significantly affecting the composition of secreted proteins. Shear-assisted enrichment of lipoaspirate constitutes no substantial manipulation of the cells' secretome.

Autologous adipose stem cell therapy for knee osteoarthritis: where are we now?

Introduction: The purpose of this study was to evaluate the efficacy and safety of adipose-derived stem cell (ADSC) or stromal vascular fraction (SVF) injections for knee osteoarthritis (OA) treatment by analyzing all randomized controlled trials dealing with this topic. Materials and methods: The following search terms were used in PUBMED, EMBASE, Scopus, and the Cochrane Library Database on 14 November 2019: 'adipose derived stem cell' OR 'stromal vascular fraction' OR 'SVF' OR 'multipotent mesenchymal stromal cells' OR 'stem cell' OR 'derived stem cell' OR 'autologous' AND 'knee' OR 'osteoarthritis' OR 'chondral defect' OR 'randomized' OR 'controlled trial.' No time limit was given to publication date. We included randomized controlled trials (RCTs) based on the following criteria: (1) English studies; (2) patient population diagnosed with knee OA and treated with ADSCs or SVF injections; (3) comparison group treated with placebo, surgery, or adjuvant injections, such as platelet rich-plasma or hyaluronic acid. Results: Intra-articular injections of adipose stem cell therapy in the form of ADSC or SVF is a safe procedure for the treatment of knee OA, with good clinical and radiological outcomes in the early follow-up period (12-24 months). In addition, treatment with fat-derived cells showed a very low complication rate (16.15%) of which all were considered to be minor. Conclusions: ADSCs and SVF seem to produce promising good to excellent clinical results for the treatment of knee OA. However, the length and modalities of follow-up in the different conditions are extremely variable. Nevertheless, it appears that the use of adipose-derived stem cells is associated with clinical and radiological improvements and minimal complication rates. To avoid bias deriving from the use of biological adjuvants or surgical procedures, randomized controlled trials comparing ADSCs or SVF and other treatments (for example, platelet rich-plasma or hyaluronic acid injections) should be performed.

The EZMTT cell proliferation assay provides precise measurement for drug combinations and better correlation between in vitro and in vivo efficacy

The rate of drug-induced proliferation (DIP) has been proposed as an unbiased alternative drug effect metric. However, current assays are not easy and precise enough to track minor changes in cell growth. Here, we report the optimized EZMTT based detection method which can continuously measure time-dependent growth after drug treatment and reliably detect partial drug resistance for cancer cells. Importantly, tracking time-dependent growth after drug treatment demonstrated that a KGA allosteric inhibitor alone failed to completely inhibit cancer cell growth, but a drug combination was able to provide complete inhibition in cell-based assays that translated well in in vivo animal experiments. In conclusion, this simple EZMTT method provided precise measurement of loss of susceptibility after drug treatment and has great potential to be developed for drug efficacy and drug combination studies to solve the unmet medical need.

Measured Levels of Human Adipose Tissue-Derived Stem Cells in Adipose Tissue Is Strongly Dependent on Harvesting Method and Stem Cell Isolation Technique

BACKGROUND

Adipose tissue-derived stem cells are of great interest because of their properties of immune modulation, tissue regeneration, and multipotent differentiation. To advance development of stem cell-based treatments, determination of the physiologic concentration of adipose tissue-derived stem cells in human adipose tissue is relevant for proper guidance of stem cell treatment dosage, oncologic safety, and evaluation of efficacy.

METHODS

A prospective comparative case-control study of 20 patients was conducted to determine the yield of adipose tissue-derived stem cells in periumbilical adipose tissue harvested by the widely used method of aspiration and in structurally intact adipose tissue harvested by excision. Stem cells were isolated using conventional enzymatic digestion and by a method combining enzymatic digestion with mechanical distortion. Stem cell yield was quantified by multicolor flow cytometry and colony-forming capacity.

RESULTS

When only the conventional enzymatic digestion was used, no significant difference in adipose tissue-derived stem cell yield was observed. However, when enzymatic digestion was combined with mechanical distortion, twice as many stem cells were isolated from excised adipose tissue compared to aspirated adipose tissue. Inclusion of mechanical distortion significantly increased yield 5-fold in excised adipose tissue and 2-fold in aspirated adipose tissue. Combining enzymatic digestion and mechanical distortion, measured levels of excised adipose tissue reached 140 × 10 (95 percent CI, 62 to 220 × 10) adipose tissue-derived stem cells per gram of adipose tissue that corresponded to 26 × 10 (95 percent CI, 18 to 33 × 10) colony-forming units per gram.

CONCLUSIONS

The study indicates that harvesting by aspiration halves the concentration of adipose tissue-derived stem cells in adipose tissue samples when compared to structural intact adipose tissue. Furthermore, the study presents stem cell yield higher than previously described in the current literature.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Adipocyte-Based Cell Therapy in Oncology: The Role of Cancer-Associated Adipocytes and Their Reinterpretation as Delivery Platforms

Cancer-associated adipocytes have functional roles in tumor development through secreted adipocyte-derived factors and exosomes and also through metabolic symbiosis, where the malignant cells take up the lactate, fatty acids and glutamine produced by the neighboring adipocytes. Recent research has demonstrated the value of adipocytes as cell-based delivery platforms for drugs (or prodrugs), nucleic acids or loaded nanoparticles for cancer therapy. This strategy takes advantage of the biocompatibility of the delivery system, its ability to locate the tumor site and also the predisposition of cancer cells to come in functional contact with the adipocytes from the tumor microenvironment for metabolic sustenance. Also, their exosomal content can be used in the context of cancer stem cell reprogramming or as a delivery vehicle for different cargos, like non-coding nucleic acids. Moreover, the process of adipocytes isolation, processing and charging is quite straightforward, with minimal economical expenses. The present review comprehensively presents the role of adipocytes in cancer (in the context of obese and non-obese individuals), the main methods for isolation and characterization and also the current therapeutic applications of these cells as delivery platforms in the oncology sector.

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.

Adipose-derived mesenchymal stem cell exosomes: a novel pathway for tissues repair

The well-characterized curative effect of transplanted mesenchymal stem cells has been mainly attributed to their homing and subsequent differentiation for the repair and regeneration of damaged tissue. Adipose-derived mesenchymal stem cells (ADMSCs) are not only multipotent and plastic, but also abundant as they can be easily harvested with minimally invasive surgical techniques. This makes ADMSCs conducive for clinical applications. Recently, the secretory function of ADMSCs has been regarded as the primary mediator of MSC-based therapy. Exosomes are one kind of small cell extracellular membrane vesicles, which are primarily used to deliver cell-specific proteins, as well as nucleic acids secreted by various cell types. This review will introduce and characterize exosomes-derived ADMSCs (ADMSCs-Exo) and look at new therapies and prospective, including the limitations and outlook for therapeutic strategy. We will describe the latest research progress on myocardial repair, neuroprotection and neurotrophic effects, hepatic repair, renal repair, cutaneous repair, regeneration and other aspects using these cells.

Limited evidence for adipose-derived stem cell therapy on the treatment of osteoarthritis

PURPOSE

The purpose of this systematic review is to evaluate the effects of adipose derived mesenchymal stem cells (ADSCs) in the treatment of osteoarthritis (OA) in the clinical setting.

METHODS

A literature search was performed in the MEDLINE, EMBASE, and The Cochrane Library Database up to January 2017 for inclusion and exclusion criteria. Criteria for inclusion were clinical studies demonstrating the effects of ADSCs on OA, and written in English. The following variables were analyzed: donor site, volume of adipose tissue, preparation of ADSCs, clinical outcomes, and complication rate.

RESULTS

Sixteen studies (knee: 14 studies, multiple joints: 1 study, ankle: 1 study) were included in this systematic review. All of the studies prepared ADSCs in the form of the stromal vascular fraction (SVF). Inconsistencies between studies were found with regards to reported clinical variability, donor sites of SVF, and reported clinical outcomes. Nine studies used either platelet-rich plasma (PRP) (7/16) or fibrin (4/16) or both PRP and Fibrin (1/16), as an adjunct at time of SVF injection. All of the studies reported an improvement in clinical outcomes with the use of SVF. Five studies reported a 90% satisfaction rate, and no study reported any complications with liposuction. Five studies reported on complications, with a 5% incidence of swelling and pain.

CONCLUSIONS

This systematic review demonstrated that ADSCs are currently used in the form of SVF. While SVF may produce favorable clinical outcomes with minimal risk of side effects on osteoarthritis, the variability in the data and the use of biological adjuvants have confounded the effectiveness of ADSCs. This study will help surgeons understand the limitations in the literature on ADSCs.

LEVEL OF EVIDENCE

Level IV, systematic review of level IV studies.

Revisiting the Advances in Isolation, Characterization and Secretome of Adipose-Derived Stromal/Stem Cells

Adipose-derived stromal/stem cells (ASCs) seems to be a promising regenerative therapeutic agent due to the minimally invasive approach of their harvest and multi-lineage differentiation potential. The harvested adipose tissues are further digested to extract stromal vascular fraction (SVF), which is cultured, and the anchorage-dependent cells are isolated in order to characterize their stemness, surface markers, and multi-differentiation potential. The differentiation potential of ASCs is directed through manipulating culture medium composition with an introduction of growth factors to obtain the desired cell type. ASCs have been widely studied for its regenerative therapeutic solution to neurologic, skin, wound, muscle, bone, and other disorders. These therapeutic outcomes of ASCs are achieved possibly via autocrine and paracrine effects of their secretome comprising of cytokines, extracellular proteins and RNAs. Therefore, secretome-derivatives might offer huge advantages over cells through their synthesis and storage for long-term use. When considering the therapeutic significance and future prospects of ASCs, this review summarizes the recent developments made in harvesting, isolation, and characterization. Furthermore, this article also provides a deeper insight into secretome of ASCs mediating regenerative efficacy.

A Novel Porcine Model for Future Studies of Cell-enriched Fat Grafting

Supplemental Digital Content is available in the text.

Background:

Cell-enriched fat grafting has shown promising results for improving graft survival, although many questions remain unanswered. A large animal model is crucial for bridging the gap between rodent studies and human trials. We present a step-by-step approach in using the Göttingen minipig as a model for future studies of cell-enriched large volume fat grafting.

Methods:

Fat grafting was performed as bolus injections and structural fat grafting. Graft retention was assessed by magnetic resonance imaging after 120 days. The stromal vascular fraction (SVF) was isolated from excised fat and liposuctioned fat from different anatomical sites and analyzed. Porcine adipose-derived stem/stromal cells (ASCs) were cultured in different growth supplements, and population doubling time, maximum cell yield, expression of surface markers, and differentiation potential were investigated.

Results:

Structural fat grafting in the breast and subcutaneous bolus grafting in the abdomen revealed average graft retention of 53.55% and 15.28%, respectively, which are similar to human reports. Liposuction yielded fewer SVF cells than fat excision, and abdominal fat had the most SVF cells/g fat with SVF yields similar to humans. Additionally, we demonstrated that porcine ASCs can be readily isolated and expanded in culture in allogeneic porcine platelet lysate and fetal bovine serum and that the use of 10% porcine platelet lysate or 20% fetal bovine serum resulted in population doubling time, maximum cell yield, surface marker profile, and trilineage differentiation that were comparable with humans.

Conclusions:

The Göttingen minipig is a feasible and cost-effective, large animal model for future translational studies of cell-enriched fat grafting.

Adipose-derived stem cells in orthopaedic pathologies

INTRODUCTION

To examine the current literature regarding the clinical application of adipose-derived stem cells (ADSCs) for the management of orthopaedic pathologies.

SOURCES OF DATA

MEDLINE,SCOPUS, CINAHL and EMBASE (1950 to April 14, 2017) were searched by two independent investigators for articles published in English. Reviews, meta-analyses, expert opinions, case reports, mini case series and editorials were excluded. Furthermore, we excluded animal studies, cadaveric studies and in vitro studies.

AREAS OF AGREEMENT

ADSCs seem to produce excellent clinical results. However, the length and modalities of follow-up in the different conditions are extremely variable. Nevertheless, it appears that the use of adipose-derived stem cells is associated with subjective and objective clinical improvements and minimal complication rates.

AREAS OF CONTROVERSY

None of the studies identified is a randomized double-blinded trial, and most of the selected studies present major limitations, and different methods, confounding the results of our review.

GROWING POINTS

It is necessary to conduct more and better studies to ascertain whether ADSCs really play a role in orthopaedic surgery with particular attention to ADSCs harvesting method, type of administration and the conditions treated.

AREAS TIMELY FOR DEVELOPING RESEARCH

The current literature regarding the use of ADSCs for orthopaedic pathologies is limited. At present, long-term safety is the biggest challenge of ADSCs based regenerative medicine.

LEVEL OF EVIDENCE

Level IV-Study of Level I, II, III, IV.

Effects of different concentrations of Platelet-rich Plasma and Platelet-Poor Plasma on vitality and differentiation of autologous Adipose tissue-derived stem cells

BACKGROUND

Autologous fat grafts and adipose-derived stem cells (ASCs) can be used to treat soft tissue defects. However, the results are inconsistent and sometimes comprise tissue resorption and necrosis. This might be due to insufficient vascularization. Platelet-rich plasma (PRP) is a source of concentrated autologous platelets. The growth factors and cytokines released by platelets can facilitate angiogenesis. The simultaneous use of PRP might improve the regeneration potential of fat grafts. The optimal ratio has yet to be elucidated. A byproduct of PRP preparation is platelet-poor plasma (PPP).

OBJECTIVE

In this study we investigated the influence of different concentrations of PRP on the vitality and differentiation of ASCs.

METHODS

We processed whole blood with the Arthrex Angel centrifuge and isolated ASCs from the same donor. We tested the effects of different PRP and PPP concentrations on the vitality using resazurin assays and the differentiation of ASCs using oil-red staining.

RESULTS

Both cell vitality and adipogenic differentiation increase to a concentration of 10% to 20% PRP. With a PRP concentration of 30% cell vitality and differentiation decrease.

CONCLUSIONS

Both PRP and PPP can be used to expand ASCs without xenogeneic additives in cell culture. A PRP concentration above 20% has inhibitory effects.

Inhibiting glycogen synthase kinase-3 and transforming growth factor-β signaling to promote epithelial transition of human adipose mesenchymal stem cells

BACKGROUND

This study was aimed to investigate the epithelial differentiation of human adipose-derived mesenchymal stem cells (ADSCs) by inhibiting glycogen synthase kinase-3 (GSK3) and transforming growth factor β (TGFβ) signaling.

METHODS AND RESULTS

STEMPRO human ADSCs at passage 2 were treated with CHIR99021 (GSK3 inhibitor), E-616452 (TGFβ1 receptor kinase inhibitor), A-83-01 (TGFβ type 1 receptor inhibitor), valproic acid (histone deacetylase inhibitor), tranylcypromine (monoamine oxidase inhibitor) and all-trans retinoic acid for 72 h. The mesenchymal-epithelial transition was shown by down-regulation of mesenchymal genes (Slug, Zinc Finger E-box Binding Homeobox 1 ZEB1, integrin α5 ITGA5 and vimentin VIM) and up-regulation of epithelial genes (E-cadherin, Epithelial Cell Adhesion Molecule EpCAM, Zonula Occludens-1 ZO-1, occludin, deltaN p63 δNp63, Transcription Factor 4 TCF4 and Twist Family bHLH Transcription Factor TWIST), compared to untreated ADSCs. Cell morphology and stress fiber pattern were examined and the treated cells became less migratory in scratch wound closure assay. The formation of cell junction complexes was observed under transmission electron microscopy. Global gene expression using GeneChip^® Human Genome U133 Array (Affymetrix) showed that the treatment up-regulated 540 genes (containing genes for cell cycle, cytoskeleton reorganization, chemotaxis, epithelium development and regulation of cell migration) and down-regulated 483 genes.

CONCLUSION

Human ADSCs were transited to epithelial lineage by inhibiting GSK3 and TGFβ signaling. It can be an adult stem cell source for epithelial cell-based therapy.

Semi-automated extraction and characterization of Stromal Vascular Fraction using a new medical device

INTRODUCTION

The stem cell rich Stromal Vascular Fraction (SVF) can be harvested by processing lipo-aspirate or fat tissue with an enzymatic digestion followed by centrifugation. To date neither a standardised extraction method for SVF nor a generally admitted protocol for cell application in patients exists. A novel commercially available semi-automated device for the extraction of SVF promises sterility, consistent results and usability in the clinical routine. The aim of this work was to compare the quantity and quality of the SVF between the new system and an established manual laboratory method.

MATERIAL AND METHODS

SVF was extracted from lipo-aspirate both by a prototype of the semi-automated UNiStation™ (NeoGenesis, Seoul, Korea) and by hand preparation with common laboratory equipment. Cell composition of the SVF was characterized by multi-parametric flow-cytometry (FACSCanto-II, BD Biosciences). The total cell number (quantity) of the SVF was determined as well the percentage of cells expressing the stem cell marker CD34, the leucocyte marker CD45 and the marker CD271 for highly proliferative stem cells (quality).

RESULTS

Lipo-aspirate obtained from six patients was processed with both the novel device (d) and the hand preparation (h) which always resulted in a macroscopically visible SVF. However, there was a tendency of a fewer cell yield per gram of used lipo-aspirate with the device (d: 1.1×105±1.1×105 vs. h: 2.0×105±1.7×105; p = 0.06). Noteworthy, the percentage of CD34+ cells was significantly lower when using the device (d: 57.3% ±23.8% vs. h: 74.1% ±13.4%; p = 0.02) and CD45+ leukocyte counts tend to be higher when compared to the hand preparation (d: 20.7% ±15.8% vs. h: 9.8% ±7.1%; p = 0.07). The percentage of highly proliferative CD271+ cells was similar for both methods (d:12.9% ±9.6% vs. h: 13.4% ±11.6%; p = 0.74) and no differences were found for double positive cells of CD34+/CD45+ (d: 5.9% ±1.7% vs. h: 1.7% ±1.1%; p = 0.13), CD34+/CD271+ (d: 24.1% ±12.0% vs. h: 14.2% ±8.5%; p = 0.07).

DISCUSSION

The semi-automated closed system provides a considerable amount of sterile SVF with high reproducibility. Furthermore, the SVF extracted by both methods showed a similar cell composition which is in accordance with the data from literature. This semi-automated device offers an opportunity to take research and application of the SVF one step further to the clinic.

Xenogeneic transplantation of human adipose-derived stem cell sheets accelerate angiogenesis and the healing of skin wounds in a Zucker Diabetic Fatty rat model of obese diabetes

Introduction

Diabetic patients with foot ulcers often suffer impaired wound healing due to diabetic neuropathy and blood flow disturbances. Direct injection of human adipose-derived stem cells (hASCs) effectively accelerates wound healing, although hASCs are relatively unstable.

Methods

We developed an optimized protocol to engineer hASC sheets using temperature-responsive culture dishes to enhance the function and stability of transplanted cells used for regenerative medicine. Here, we evaluated the efficacy of hASC sheets for enhancing wound healing. For this purpose, we used a xenogeneic model of obese type 2 diabetes, the Zucker Diabetic Fatty rat (ZDF rat), which displays full-thickness skin defects. We isolated hASCs from five donors, created hASC sheets, and transplanted the hASC sheets along with artificial skin into full-thickness, large skin defects (15-mm diameter) of ZDF rats.

Results

The hASC sheets secreted angiogenic growth factors. Transplantation of the hASC sheets combined with artificial skin increased blood vessel density and dermal thickness, thus accelerating wound healing compared with that in the controls. Immunohistochemical analysis revealed significantly more frequent neovascularization in xenografted rats of the transplantation group, and the transplanted hASCs were localized to the periphery of new blood vessels.

Conclusion

This xenograft model may contribute to the use of human cell tissue-based products (hCTPs) and the identification of factors produced by hCTPs that accelerate wound healing.

•

We established a protocol for human adipose-derived stem cells (hASC) sheets.

•

The hASC sheets secreted angiogenic growth factors.

•

Xenogeneic hASC sheet transplantation accelerated wound healing in diabetic rats.

Promising Therapeutic Strategies for Mesenchymal Stem Cell-Based Cardiovascular Regeneration: From Cell Priming to Tissue Engineering

The primary cause of death among chronic diseases worldwide is ischemic cardiovascular diseases, such as stroke and myocardial infarction. Recent evidence indicates that adult stem cell therapies involving cardiovascular regeneration represent promising strategies to treat cardiovascular diseases. Owing to their immunomodulatory properties and vascular repair capabilities, mesenchymal stem cells (MSCs) are strong candidate therapeutic stem cells for use in cardiovascular regeneration. However, major limitations must be overcome, including their very low survival rate in ischemic lesion. Various attempts have been made to improve the poor survival and longevity of engrafted MSCs. In order to develop novel therapeutic strategies, it is necessary to first identify stem cell modulators for intracellular signal triggering or niche activation. One promising therapeutic strategy is the priming of therapeutic MSCs with stem cell modulators before transplantation. Another is a tissue engineering-based therapeutic strategy involving a cell scaffold, a cell-protein-scaffold architecture made of biomaterials such as ECM or hydrogel, and cell patch- and 3D printing-based tissue engineering. This review focuses on the current clinical applications of MSCs for treating cardiovascular diseases and highlights several therapeutic strategies for promoting the therapeutic efficacy of MSCs in vitro or in vivo from cell priming to tissue engineering strategies, for use in cardiovascular regeneration.

A Comparative Study on the Biological Characteristics of Human Adipose-Derived Stem Cells from Lipectomy and Liposuction

PURPOSES

To compare the biological behaviors of human adipose-derived stem cells (ADSCs) isolated from adipose tissue by lipectomy and liposuction, with the purpose of providing the basis for clinical application.

METHODS

The proliferation and apoptosis of ADSCs were analyzed by CCK-8 assay and flow cytometry. Cell migration was measured by a wound healing assay. An ELISA assay was used to evaluate paracrine functions. SOD and MDA were tested by xanthine oxidase and thiobarbituric acid reactions, respectively. In addition, we used a CCK-8, LDH assay and flow cytometry to analyze the proliferation and apoptosis of ADSCs treated with lidocaine or adrenaline.

RESULTS

The viable ADSCs yield from liposuction was significantly lower than that from lipectomy, while the apoptosis of cells from liposuction was significantly higher than from lipectomy. The paracrine secretion of the two sources of ADSCs was highest when treated with 10-7 mol/L insulin and 10 ng/mL TGF-α, but there were no significant differences in VEGF, IL-6, IL-8 or HGF levels. The ADSCs from lipectomy migrated faster than those from liposuction, and SOD in the lipectomy group was higher than in the liposuction group, whereas MDA of the lipectomy group was lower than that of the liposuction group. The proliferation ADSCs treated with lidocaine or adrenaline was greatly decreased, while apoptosis was significantly increased, and cytotoxicity of lidocaine or adrenaline to ADSCs was dose-dependent.

CONCLUSIONS

Compared with ADSCs from liposuction, the ADSCs from lipectomy have better biological characteristics. Lidocaine and adrenaline decreased the viability of ADSCs, and their cytotoxicity to ADSCs was dose-dependent.

Transcription Profile in Sporadic Multiple Symmetric Lipomatosis Reveals Differential Expression at the Level of Adipose Tissue-Derived Stem Cells

BACKGROUND

The cause of the rare fat distribution disorder multiple symmetric lipomatosis is unknown. Independent reports suggest a higher proliferative activity, hormone resistance, and involvement of mitochondrial function in the disease.

METHODS

The authors performed morphologic comparison of affected and unaffected tissues in five unrelated patients and generated adipose-derived stem cell cultures from the tissue samples and characterized them as a possible cellular model of multiple symmetric lipomatosis evolution. The authors investigated proliferative activity and the expression of genes relevant to disease processes.

RESULTS

There was no difference in the morphologic appearance and the surface marker profile. Stem cells from lipomatous tissue showed significantly higher proliferative activity. Polymerase chain reaction arrays showed marked changes in genes associated with proliferation, hormonal regulation, and mitochondria. The authors show that multiple symmetric lipomatosis tissue is morphologically and histologically different from regular subcutaneous fat.

CONCLUSIONS

This study indicates an involvement of mesenchymal stem cells in the pathogenesis of multiple symmetric lipomatosis and that the evolution of multiple symmetric lipomatosis tissue is a process driven by an inherent defect of the respective cell clone(s). Further molecular genetics and functional analysis will be required to unravel the pathogenetic mechanism underlying the derailment in fat cell metabolism and proliferation. Here, the authors show for the first time that adipose-derived stem cells exhibit many characteristics previously described for native multiple symmetric lipomatosis fat tissue and propose that they are therefore an excellent tool for further functional investigations in multiple symmetric lipomatosis and other disorders of the fat tissue.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, V.

Dual-crosslinked hydrogel microwell system for formation and culture of multicellular human adipose tissue-derived stem cell spheroids

Three-dimensional (3D) multicellular spheroids of human adipose tissue-derived stem cells (hASCs) are an attractive system for basic science studies and tissue engineering applications, as they can resemble cellular condensations present in developmental and healing processes. The purpose of this study was to engineer a hydrogel-based microwell platform by capitalizing on the differential swelling behavior of micropatterned dual-crosslinked oxidized, methacrylated alginate (OMA)/multi-arm polyethylene glycol (PEG) hydrogels for rapid formation of uniform multicellular hASC spheroids with controllable size and evaluation of the capacity of the system to be used to drive osteogenic differentiation of the spheroids. By changing the micropattern size, the size of the hydrogel microwells was easily controllable. Microwell-seeded hASCs generated spheroids of relatively uniform size and high cell viability. hASC spheroids exhibited rapid mineralization in osteogenic media, which was faster than that of conventional two-dimensionally cultured hASCs. This new hydrogel microwell system has great potential for controlled multicellular spheroid formation and defined signal presentation from the hydrogel material to the cell aggregates to regulate tissue formation.

Stem cell-based therapies for the newborn lung and brain: Possibilities and challenges

There have been substantial advances in neonatal medical care over the past 2 decades that have resulted in the increased survival of very low birth weight infants, survival that in some centers extends to 22 weeks gestational age. Despite these advances, there continues to be significant morbidity associated with extreme preterm birth that includes both short-term and long-term pulmonary and neurologic consequences. No single therapy has proven to be effective in preventing or treating either developmental lung and brain injuries in preterm infants or the hypoxic-ischemic injury that can be inflicted on the full-term brain as a result of in utero or perinatal complications. Stem cell-based therapies are emerging as a potential paradigm-shifting approach for such complex diseases with multifactorial etiologies, but a great deal of work is still required to understand the role of stem/progenitor cells in normal development and in the repair of injured tissue. This review will summarize the biology of the various stem/progenitor cells, their effects on tissue repair in experimental models of lung and brain injury, the recent advances in our understanding of their mechanism of action, and the challenges that remain to be addressed before their eventual application to clinical care.

Adipose-Derived Stem Cells for Tissue Engineering and Regenerative Medicine Applications

Adipose-derived stem cells (ASCs) are a mesenchymal stem cell source with properties of self-renewal and multipotential differentiation. Compared to bone marrow-derived stem cells (BMSCs), ASCs can be derived from more sources and are harvested more easily. Three-dimensional (3D) tissue engineering scaffolds are better able to mimic the in vivo cellular microenvironment, which benefits the localization, attachment, proliferation, and differentiation of ASCs. Therefore, tissue-engineered ASCs are recognized as an attractive substitute for tissue and organ transplantation. In this paper, we review the characteristics of ASCs, as well as the biomaterials and tissue engineering methods used to proliferate and differentiate ASCs in a 3D environment. Clinical applications of tissue-engineered ASCs are also discussed to reveal the potential and feasibility of using tissue-engineered ASCs in regenerative medicine.

Adipose Mesenchymal Stem Cells Isolated after Manual or Water-jet-Assisted Liposuction Display Similar Properties

Mesenchymal stem or stromal cells (MSC) are under investigation in many clinical trials for their therapeutic potential in a variety of diseases, including autoimmune and inflammatory disorders. One of the main sources of MSCs is the adipose tissue, which is mainly obtained by manual liposuction using a cannula linked to a syringe. However, in the past years, a number of devices for fat liposuction intended for clinical use have been commercialized but few papers have compared these procedures in terms of stromal vascular fraction (SVF) or adipose mesenchymal stromal cells (ASC). The objective of the present study was to compare and qualify for clinical use the ASC obtained from fat isolated with the manual or the Bodyjet^® water-jet-assisted procedure. Although the initial number of cells obtained after collagenase digestion was higher with the manual procedure, the percentage of dead cells, the number of colony forming unit-fibroblast and the phenotype of cells were identical in the SVF at isolation (day 0) and in the ASC populations at day 14. We also showed that the osteogenic and adipogenic differentiation potentials of ASCs were identical between preparations while a slight but significant higher in vitro immunosuppressive effect was observed with ASCs isolated from fat removed with a cannula. The difference in the immunomodulatory effect between ASC populations was, however, not observed in vivo using the delayed-type hypersensitivity (DTH) model. Our data, therefore, indicate that the procedure for fat liposuction does not impact the characteristics or the therapeutic function of ASCs.

Cartilage Regeneration in Human with Adipose Tissue-Derived Stem Cells: Current Status in Clinical Implications

Osteoarthritis (OA) is one of the most common debilitating disorders among the elderly population. At present, there is no definite cure for the underlying causes of OA. However, adipose tissue-derived stem cells (ADSCs) in the form of stromal vascular fraction (SVF) may offer an alternative at this time. ADSCs are one type of mesenchymal stem cells that have been utilized and have demonstrated an ability to regenerate cartilage. ADSCs have been shown to regenerate cartilage in a variety of animal models also. Non-culture-expanded ADSCs, in the form of SVF along with platelet rich plasma (PRP), have recently been used in humans to treat OA and other cartilage abnormalities. These ADSCs have demonstrated effectiveness without any serious side effects. However, due to regulatory issues, only ADSCs in the form of SVF are currently allowed for clinical uses in humans. Culture-expanded ADSCs, although more convenient, require clinical trials for a regulatory approval prior to uses in clinical settings. Here we present a systematic review of currently available clinical studies involving ADSCs in the form of SVF and in the culture-expanded form, with or without PRP, highlighting the clinical effectiveness and safety in treating OA.

[Potential of adipose-derived stem cells concerning the treatment of wound healing complications after radiotherapy]

BACKGROUND

Compromised wound healing in irradiated tissues is a common and challenging clinical problem. The pathophysiology and underlying cellular mechanisms including the complex interaction of cytokines and growth factors are still incompletely understood.

OBJECTIVES

In this article, the potential of adipose-derived stem cells concerning the treatment of wound healing complications after radiotherapy is discussed.

METHODS

Human dermal fibroblasts (NHF), microvascular endothelial cells (HDMEC) and human adipose-derived stem cells (ASC) were cultured in a co-culture setting and irradiated with doses of 2-12Gy. Cell count was determined and levels of cytokines and growth factors relevant for wound healing were measured using enzyme-linked immunosorbent assays (ELISA) and qPCR techniques. Irradiated NHF, HDMEC and ASC as well as non-irradiated mono and co-cultures, NHF, HDMEC or ASC respectively were used as controls.

RESULTS

Cell count was significantly reduced in irradiated co-cultures of NHF, HDMEC and ASC compared to non-irradiated controls. Levels of IL-6, bFGF, ICAM-1 and VCAM-1 in the supernatants of the co-cultures were significantly less affected by external radiation in comparison to HDMEC. Levels of IL-6 and VEGF in the supernatants of co-cultures were significantly less affected by external radiation in comparison to NHF.

DISCUSSION

The increased expression of cytokines and adhesion molecules by NHF and HDMEC after external radiation is mitigated in the co-culture setting with ASC. These in vitro changes seem to support the clinical observation that ASC may have a stabilizing effect when injected into irradiated wounds.

Isolation and differentiation potential of human mesenchymal stem cells from adipose tissue harvested by water jet-assisted liposuction

BACKGROUND

In recent years the therapeutic application of extracted adipose tissue for autologous fat grafting and the application of adipose tissue-derived mesenchymal stem cells (adMSC) isolated thereof has progressed. Water-jet assisted liposuction (WAL) is 1 procedure for harvesting adipose tissue and provides a favorable aesthetic outcome combined with high tissue protection. Tissue aspirated by WAL has been successfully applied in grafting procedures.

OBJECTIVES

The aims of this study were to confirm the tissue viability and to understand the abundance and mesenchymal differentiation capacity of stem cells within the tissue.

METHODS

We analyzed tissue integrity of WAL tissue particles via fluorescence microscopy. The adMSC content was determined by isolating the cells from the tissue. The mesenchymal differentiation capacity was confirmed with cytochemical staining methods.

RESULTS

The stromal vascular fraction of WAL tissue showed high viability and contained an average of 2.6 × 105 CD34-positive cells per milliliter of tissue. Thus WAL tissue contains a high number of stem cells. Furthermore adMSC isolated from WAL tissue showed typical mesenchymal differentiation potential.

CONCLUSIONS

WAL of adipose tissue is well suited for autologous fat grafting because it retains tissue viability. Furthermore it is a valid source for the subsequent isolation of adMSC with multipotent differentiation potential.

LEVEL OF EVIDENCE

3 Therapeutic.

Power-Assisted Liposuction Versus Tissue Resection for the Isolation of Adipose Tissue-Derived Mesenchymal Stem Cells: Phenotype, Senescence, and Multipotency at Advanced Passages

BACKGROUND

Adipose tissue-derived mesenchymal stem cells (ASCs) can be isolated from subcutaneous fat harvested by tissue resection or liposuction.

OBJECTIVES

The authors compared ASCs isolated by tissue resection or power-assisted liposuction (PAL) to determine whether either surgical procedure yielded ASCs with improved purity and competence that was preserved for several passages.

METHODS

For this experimental study, ASCs were isolated from fat harvested by tissue resection or PAL from six patients who underwent abdominoplasty. ASCs were counted to determine cell yields, and viabilities were assessed with an amine-reactive dye and by fluorescence-activated cell sorting (FACS). Cell phenotypes were determined by immunostaining and FACS, and doubling times were calculated. Senescence ratios of the cells were detected by gene profiling and by assaying β-galactosidase activity. Multipotency was evaluated by induced differentiation analyses.

RESULTS

No significant differences were observed in cell numbers or viabilities of ASCs isolated following either surgical method of fat harvesting. Both populations of cultured ASCs expressed markers of mesenchymal stem cells and preserved this expression pattern through the third passage. PAL and tissue resection yielded ASCs with similar division rates, similar senescence ratios into the fourth passage, and similar capacities to differentiate into osteocytes or adipocytes.

CONCLUSIONS

Fat harvested by PAL or tissue resection yielded uniform cultures of ASCs with high division rates, low senescence ratios, and multipotency preserved into passages 3 and 4. Because PAL is less invasive, it may be preferable for the isolation of ASCs.

Human bone marrow- and adipose-mesenchymal stem cells secrete exosomes enriched in distinctive miRNA and tRNA species

Introduction

Administration of mesenchymal stem cells (MSCs) represents a promising treatment option for patients suffering from immunological and degenerative disorders. Accumulating evidence indicates that the healing effects of MSCs are mainly related to unique paracrine properties, opening opportunities for secretome-based therapies. Apart from soluble factors, MSCs release functional small RNAs via extracellular vesicles (EVs) that seem to convey essential features of MSCs. Here we set out to characterize the full small RNAome of MSC-produced exosomes.

Methods

We set up a protocol for isolating exosomes released by early passage adipose- (ASC) and bone marrow-MSCs (BMSC) and characterized them via electron microscopy, protein analysis and small RNA-sequencing. We developed a bioinformatics pipeline to define the exosome-enclosed RNA species and performed the first complete small RNA characterization of BMSCs and ASCs and their corresponding exosomes in biological replicates.

Results

Our analysis revealed that primary ASCs and BMSCs have highly similar small RNA expression profiles dominated by miRNAs and snoRNAs (together 64-71 %), of which 150–200 miRNAs are present at physiological levels. In contrast, the miRNA pool in MSC exosomes is only 2-5 % of the total small RNAome and is dominated by a minor subset of miRNAs. Nevertheless, the miRNAs in exosomes do not merely reflect the cellular content and a defined set of miRNAs are overrepresented in exosomes compared to the cell of origin. Moreover, multiple highly expressed miRNAs are precluded from exosomal sorting, consistent with the notion that these miRNAs are involved in functional repression of RNA targets. While ASC and BMSC exosomes are similar in RNA class distribution and composition, we observed striking differences in the sorting of evolutionary conserved tRNA species that seems associated with the differentiation status of MSCs, as defined by Sox2, POU5F1A/B and Nanog expression.

Conclusions

We demonstrate that primary MSCs release small RNAs via exosomes, which are increasingly implicated in intercellular communications. tRNAs species, and in particular tRNA halves, are preferentially released and their specific sorting into exosomes is related to MSC tissue origin and stemness. These findings may help to understand how MSCs impact neighboring or distant cells with possible consequences for their therapeutic usage.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0116-z) contains supplementary material, which is available to authorized users.

Obesity reduces the pro-angiogenic potential of adipose tissue stem cell-derived extracellular vesicles (EVs) by impairing miR-126 content: impact on clinical applications

BACKGROUND/OBJECTIVES

Soluble factors and cell-derived extracellular vesicles (EVs) are crucial tissue repair mediators in cell-based therapy. In the present study, we investigate the therapeutic impact of EVs released by adipose tissue-derived stem cells (ASCs) recovered from obese subjects' visceral and subcutaneous tissues.

METHODS

ASCs were recovered from 10 obese (oASCs) and 6 non-obese (nASCs) participants and characterized. In selected experiments, nASCs and oASCs were cultured with palmitic acid (PA) or high glucose (HG), respectively. EVs from obese (oEVs) and non-obese (nEVs) subjects' visceral and subcutaneous ASCs were collected after ultracentrifugation and analyzed for their cargo: microRNA-126 (miR-126), vascular endothelial growth factor (VEGF), and matrix metalloproteinase 2 (MMP-2), and for their biological effects on endothelial cells (ECs). Western blotting analysis and loss- and gain-of function experiments were performed.

RESULTS

oEVs show impaired angiogenic potential compared with nEVs. This effect depends on EV cargo: reduced content of VEGF, MMP-2 and, more importantly, miR-126. We demonstrate, using gain- and loss-of-function experiments, that this reduced miR-126 content leads to Spred1 upregulation and the inhibition of the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase pathway in ECs. We also show that PA treatment of nASCs translates into the release of EVs that recapitulate oEV cargo. Moreover, HG treatment of oASCs further reduces miR-126 EV content and EV-mediated in vitro angiogenesis. Finally, impaired pro-angiogenic potential is also detected in EVs released from obese subcutaneous adipose tissue-derived ASCs.

CONCLUSIONS

These results indicate that obesity impacts on EV pro-angiogenic potential and may raise concerns about the use of adipose tissue-derived EVs in cell-based therapy in the obese setting.

Critical steps in the isolation and expansion of adipose-derived stem cells for translational therapy

Since the discovery of adipose-derived stem cells (ASCs), there have been high expectations of their putative clinical use. Recent advances support these expectations, and it is expected that the transition from pre-clinical and clinical studies to implementation as a standard treatment modality is imminent. However ASCs must be isolated and expanded according to good manufacturing practice guidelines and a basic assurance of quality, safety, and medical effectiveness is needed for authorisation by regulatory agencies, such as European Medicines Agency and US Food and Drug Administration. In this review, a collection of studies investigating the influence of different steps of the isolation and expansion protocol on the yield and functionality of ASCs has been presented in an attempt to come up with best recommendations that ensure potential beneficial clinical outcome of using ASCs in any therapeutic setting. If the findings confirm the initial observations of beneficial effects of ASCs, the path is paved for implementing these ASC-based therapies as standard treatment options.