From heterogeneity to plasticity in adipose tissues: site-specific differences

Adipose tissue plasticity: how fat depots respond differently to pathophysiological cues

White adipose tissue (WAT) has key metabolic and endocrine functions and plays a role in regulating energy homeostasis and insulin sensitivity. WAT is characterised by its capacity to adapt and expand in response to surplus energy through processes of adipocyte hypertrophy and/or recruitment and proliferation of precursor cells in combination with vascular and extracellular matrix remodelling. However, in the context of sustained obesity, WAT undergoes fibro-inflammation, which compromises its functionality, contributing to increased risk of type 2 diabetes and cardiovascular diseases. Conversely, brown adipose tissue (BAT) and browning of WAT represent potential therapeutic approaches, since dysfunctional white adipocyte-induced lipid overspill can be halted by BAT/browning-mediated oxidative anti-lipotoxic effects. Better understanding of the cellular and molecular pathophysiological mechanisms regulating adipocyte size, number and depot-dependent expansion has become a focus of interest over recent decades. Here, we summarise the mechanisms contributing to adipose tissue (AT) plasticity and function including characteristics and cellular complexity of the various adipose depots and we discuss recent insights into AT origins, identification of adipose precursors, pathophysiological regulation of adipogenesis and its relation to WAT/BAT expandability in obesity and its associated comorbidities.

Transplantation of adipose tissue-derived stromal cells promotes the survival of venous-congested skin flaps in rabbit ear

Venous congestion after skin flap transplantation usually slows blood flow velocity and induces skin flap necrosis and surgical failure. Adipose tissue-derived stromal cells (ADSCs) can promote neovascularization and have been extensively applied in cell transplantation therapy and tissue regeneration. However, their function has not been reported in venous-congested skin flaps. In this study, rabbit ADSCs were isolated and identified. We established a rabbit ear venous-congested skin flap model and injected ADSCs into points along the midlines of skin flaps. The survival conditions of venous-congested skin flaps on postoperative day 7 showed that there was obvious swelling, hemorrhage, or necrosis in skin flaps of the control group, while the skin flap survival rate in the ADSC treatment group significantly increased. Hematoxylin and eosin (HE) staining results indicated that compared with the control group, thrombosis was significantly relieved and neovascularization was observed in the ADSC treatment group. Immunofluorescence revealed that the CD34 expression level and the number of capillaries significantly increased in the ADSC treatment group. In summary, ADSC transplantation promotes neovascularization in venous-congested skin flaps and skin flap survival. Therefore, ADSC transplantation may be an effective measure for promoting the survival of venous-congested skin flaps.

Advances in Adipose-Derived Stem Cells Isolation, Characterization, and Application in Regenerative Tissue Engineering

Obesity is a complex, multifactorial disease that has been extensively researched in recent times. Obesity is characterized by excess deposition of adipose tissue in response to surplus energy. Despite the negative connotations of adipose tissue (AT), it serves as a critical endocrine organ. Adipose tissue is a source of several adipokines and cytokines which have been deemed important for both normal metabolic function and disease formation. The discoveries of metabolically active brown AT in adult humans and adipose tissue derived stem cells (ADSC) have been key findings in the past decade with potential therapeutic implications. ADSCs represent an enticing pool of multipotent adult stem cells because of their noncontroversial nature, relative abundance, ease of isolation, and expandability. A decade and a half since the discovery of ADSCs, the scientific community is still working to uncover their therapeutic potential in a wide range of diseases. In this review, we provide an overview of the recent developments in the field of ADSCs and examine their potential use in transplantation and cell-based therapies for the regeneration of diseased organs and systems. We also hope to provide perspective on how to best utilize this readily available, powerful pool of stem cells in the future.

Upregulation of Bcl-2 enhances secretion of growth factors by adipose-derived stem cells deprived of oxygen and glucose

There is an increasing recognition that beneficial effects of adipose-derived stem cell (ADSC) therapy may depend largely on the secretion of multiple growth factors. This study modified ADSCs with the Bcl-2 gene in order to increase the secretion of growth factors during oxygen-glucose deprivation (OGD). The phenotypes of human ADSCs that were passaged 4 times were analyzed using flow cytometry. Then, ADSCs were genetically modified with Bcl-2 and Bcl-2 gene transduction was verified with Western blotting. Proliferative capacity and multipotent differentiation properties were evaluated in Bcl-2-modified ADSCs. Secretion of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and basic fibroblast growth factor (bFGF) was evaluated using an enzyme-linked immunosorbent assay (ELISA) during OGD. Human ADSCs that were passaged 4 times expressed stem cell-associated markers but not a fibroblast marker or a hematopoietic stem cell marker. The Bcl-2 gene was efficiently transfected into ADSCs; Bcl-2 modification did not affect the proliferative and multilineage differentiation capacity of ADSCs. In addition, Bcl-2 overexpression enhanced the secretion of VEGF, bFGF, and HGF by 14.47%, 16.9%, and 91%, respectively, compared to ADSCs alone that were deprived of oxygen and glucose. These data suggest that Bcl-2 overexpression enhances secretion of angiogenic growth factors by ADSCs deprived of oxygen and glucose.

Developments in our understanding of the effects of growth hormone on white adipose tissue from mice: implications to the clinic

Adipose tissue (AT) is a well-established target of growth hormone (GH) and is altered in clinical conditions associated with excess, deficiency and absence of GH action. Due to the difficulty in collecting AT from clinical populations, genetically modified mice have been useful in better understanding how GH affects this tissue. Recent findings in mice would suggest that the impact of GH on AT is beyond alterations of lipolysis, lipogenesis or proliferation/ differentiation. AT depot-specific alterations in immune cells, extracellular matrix, adipokines, and senescence indicate an expanded role for GH in AT physiology. This mouse data will guide additional studies necessary to evaluate the therapeutic potential and safety of GH for conditions associated with altering AT, such as obesity. In this review, we introduce several relatively new intricacies of GH's effect on AT, focusing on recent studies in mice. Finally, we summarize the clinical implications of these findings.

Advances in Adipose-Derived Stem Cells Isolation, Characterization, and Application in Regenerative Tissue Engineering

Obesity is a complex, multifactorial disease that has been extensively researched in recent times. Obesity is characterized by excess deposition of adipose tissue in response to surplus energy. Despite the negative connotations of adipose tissue (AT), it serves as a critical endocrine organ. Adipose tissue is a source of several adipokines and cytokines which have been deemed important for both normal metabolic function and disease formation. The discoveries of metabolically active brown AT in adult humans and adipose tissue derived stem cells (ADSC) have been key findings in the past decade with potential therapeutic implications. ADSCs represent an enticing pool of multipotent adult stem cells because of their noncontroversial nature, relative abundance, ease of isolation, and expandability. A decade and a half since the discovery of ADSCs, the scientific community is still working to uncover their therapeutic potential in a wide range of diseases. In this review, we provide an overview of the recent developments in the field of ADSCs and examine their potential use in transplantation and cell-based therapies for the regeneration of diseased organs and systems. We also hope to provide perspective on how to best utilize this readily available, powerful pool of stem cells in the future.

INVITED REVIEW: Evolution of meat animal growth research during the past 50 years: Adipose and muscle stem cells

If one were to compare today's animal growth research to research from a mere 50 yr ago, one would see programs with few similarities. The evolution of this research from whole-animal through cell-based and finally molecular and genomic studies has been enhanced by the identification, isolation, and in vitro evaluation of adipose- and muscle-derived stem cells. This paper will highlight the struggles and the milestones that make this evolving area of research what it is today. The contribution of adipose and muscle stem cell research to development and growth, tissue regeneration, and final carcass composition are reviewed.

Comparison of Mesenchymal Stem Cell Surface Markers from Bone Marrow Aspirates and Adipose Stromal Vascular Fraction Sites

The objective of this study was to subjectively evaluate the harvest of two areas of adipose collection and three areas of bone marrow collection as potential sites for clinical harvest of adipose stromal vascular fraction (SVF) and bone marrow concentrate for clinical use by quantifying the amount of tissue harvested, subjective ease of harvest, the variation of each site, and determining the cell surface marker characteristics using commercially available antibodies. Bone marrow and adipose tissue samples were collected from 10 adult mixed breed dogs. Adipose tissue was collected from the caudal scapular region and falciform fat ligament. Bone marrow aspirates were collected from the ilium, humerus, and tibia. Tissues were weighed (adipose) or measured by volume (bone marrow), processed to isolate the SVF or bone marrow concentrate, and flow cytometry was performed to quantitate the percentage of cells that were CD90, CD44 positive, and CD45 negative. Sites and tissue types were compared using matched pairs t-test. Subjectively subcutaneous fat collection was the most difficult and large amounts of tissue dissection were necessary. Additionally the subcutaneous area yielded less than the goal amount of tissue. The bone marrow harvest ranged from 10 to 27.5 ml. Adipose tissue had the highest concentration of cells with CD90⁺, CD44⁺, and CD45⁻ markers (P < 0.05), and bone marrow had the highest total number of these cells at harvest (P < 0.05). Variation was high for all sites, but the adipose collection yielded more consistent results. These results describe the relative cellular components in the SVF of adipose tissue and bone marrow as defined by the biomarkers chosen. Although bone marrow yielded higher absolute cell numbers on average, adipose tissue yielded more consistent results. Fat from the falciform ligament was easily obtained with less dissection and therefore created less perceived relative patient trauma.

Adipose Tissue - Adequate, Accessible Regenerative Material

The potential use of stem cell based therapies for the repair and regeneration of various tissues offers a paradigm shift that may provide alternative therapeutic solutions for a number of diseases. The use of either embryonic stem cells (ESCs) or induced pluripotent stem cells in clinical situations is limited due to cell regulations and to technical and ethical considerations involved in genetic manipulation of human ESCs, even though these cells are highly beneficial. Mesenchymal stem cells seen to be an ideal population of stem cells in particular, Adipose derived stem cells (ASCs) which can be obtained in large number and easily harvested from adipose tissue. It is ubiquitously available and has several advantages compared to other sources as easily accessible in large quantities with minimal invasive harvesting procedure, and isolation of adipose derived mesenchymal stem cells yield a high amount of stem cells which is essential for stem cell based therapies and tissue engineering. Recently, periodontal tissue regeneration using ASCs has been examined in some animal models. This method has potential in the regeneration of functional periodontal tissues because various secreted growth factors from ASCs might not only promote the regeneration of periodontal tissues but also encourage neovascularization of the damaged tissues. This review summarizes the sources, isolation and characteristics of adipose derived stem cells and its potential role in periodontal regeneration is discussed.

Effects of sex and site on amino acid metabolism enzyme gene expression and activity in rat white adipose tissue

Background and Objectives. White adipose tissue (WAT) shows marked sex- and diet-dependent differences. However, our metabolic knowledge of WAT, especially on amino acid metabolism, is considerably limited. In the present study, we compared the influence of sex on the amino acid metabolism profile of the four main WAT sites, focused on the paths related to ammonium handling and the urea cycle, as a way to estimate the extent of WAT implication on body amino-nitrogen metabolism. Experimental Design. Adult female and male rats were maintained, undisturbed, under standard conditions for one month. After killing them under isoflurane anesthesia. WAT sites were dissected and weighed. Subcutaneous, perigonadal, retroperitoneal and mesenteric WAT were analyzed for amino acid metabolism gene expression and enzyme activities. Results. There was a considerable stability of the urea cycle activities and expressions, irrespective of sex, and with only limited influence of site. Urea cycle was more resilient to change than other site-specialized metabolic pathways. The control of WAT urea cycle was probably related to the provision of arginine/citrulline, as deduced from the enzyme activity profiles. These data support a generalized role of WAT in overall amino-N handling. In contrast, sex markedly affected WAT ammonium-centered amino acid metabolism in a site-related way, with relatively higher emphasis in males' subcutaneous WAT. Conclusions. We found that WAT has an active amino acid metabolism. Its gene expressions were lower than those of glucose-lipid interactions, but the differences were quantitatively less important than usually reported. The effects of sex on urea cycle enzymes expression and activity were limited, in contrast with the wider variations observed in other metabolic pathways. The results agree with a centralized control of urea cycle operation affecting the adipose organ as a whole.

sdf1 Expression reveals a source of perivascular-derived mesenchymal stem cells in zebrafish

There is accumulating evidence that mesenchymal stem cells (MSCs) have their origin as perivascular cells (PVCs) in vivo, but precisely identifying them has been a challenge, as they have no single definitive marker and are rare. We have developed a fluorescent transgenic vertebrate model in which PVC can be visualized in vivo based upon sdf1 expression in the zebrafish. Prospective isolation and culture of sdf1(DsRed) PVC demonstrated properties consistent with MSC including prototypical cell surface marker expression; mesodermal differentiation into adipogenic, osteogenic, and chondrogenic lineages; and the ability to support hematopoietic cells. Global proteomic studies performed by two-dimensional liquid chromatography and tandem mass spectrometry revealed a high degree of similarity to human MSC (hMSC) and discovery of novel markers (CD99, CD151, and MYOF) that were previously unknown to be expressed by hMSC. Dynamic in vivo imaging during fin regeneration showed that PVC may arise from undifferentiated mesenchyme providing evidence of a PVC-MSC relationship. This is the first model, established in zebrafish, in which MSC can be visualized in vivo and will allow us to better understand their function in a native environment.

Qualitative and quantitative differences of adipose-derived stromal cells from superficial and deep subcutaneous lipoaspirates: a matter of fat

BACKGROUND AIMS

Subcutaneous fat represents a valuable reservoir of adipose-derived stem cells (ASCs) in the stromal vascular fraction (SVF), widely exploited in regenerative medicine applications, being easily harvested through lipoaspiration. The lack of standardized procedures for autologous fat grafting guided research efforts aimed at identifying possible differences related to the harvesting site, which may affect cell isolation yield, cell growth properties and clinical outcomes. Subcutaneous fat features a complex architecture: the superficial fascia separates superficial adipose tissue (SAT) from deep layer tissue (DAT). We aimed to unravel the differences between SAT and DAT, considering morphological structure, SVF composition, and ASC properties.

METHODS

SAT and DAT were collected from female donors and comparatively analyzed to evaluate cellular yield and viability, morphology, immunophenotype and molecular profile. ASCs were isolated in primary culture and used for in vitro differentiation assays. SAT and DAT from cadaver donors were also analyzed through histology and immunohistochemistry to assess morphology and cell localization within the hypoderm.

RESULTS

Liposuctioned SAT contained a higher stromal tissue compound, along with a higher proportion of CD105-positive cells, compared with DAT from the same harvesting site. Also, cells isolated from SAT displayed increased multipotency and stemness features. All differences were mainly evidenced in specimens harvested from the abdominal region. According to our results, SAT features overall increased stem properties.

CONCLUSIONS

Given that subcutaneous adipose tissue is currently exploited as the gold standard source for high-yield isolation of adult stem cells, these results may provide precious hints toward the definition of standardized protocols for microharvesting.

Therapeutic doses of multipotent stromal cells from minimal adipose tissue

Low yield of adult adipose-derived multipotent stromal cells (ASC) can limit autologous cell therapy in individuals with minimal adipose tissue. In this study, ASC isolation was optimized from approximately 0.2 g of feline epididymal adipose tissue for a treatment dose of 10⁶–10⁷ ASCs/kg. The ASC yield was determined for three digestions, 0.1 % collagenase in medium for 30 min (Classic), 0.3 % collagenase in buffer for 30 min (New) and 0.3 % collagenase in buffer for 1 h (Hour). After isolation by the new tissue digestion, continuously cultured ASCs (fresh) and cells recovered and expanded after cryostorage at P0 (revitalized) were characterized up to cell passage (P) 5. Outcomes included CD9, CD29, CD44, CD90 and CD105 expression, cell doublings and doubling times, fibroblastic, adipogenic and osteogenic colony forming unit (CFU) frequency percentages and lineage-specific target gene expression after induction. The New digestion had the highest CFU yield, and about 7x10⁶ ASCs/kg were available within three cell passages (P2). Compared to earlier passages, target surface antigen expression was lowest in fresh P5 cells, and fresh and revitalized P3–5 cells had slower expansion. Fresh and revitalized P1 ASCs had higher CFU frequency percentages and lineage-specific gene expression than P3. The New method described in this study was most efficient for feline epididymal ASC isolation and did not alter in vitro cell behavior. Fresh and revitalized P0-P2 feline ASCs may be most effective for preclinical and clinical trials. This study offers a potential option for ASC isolation from limited adipose tissue resources across species.

Human adult stem cells maintain a constant phenotype profile irrespective of their origin, Basal media, and long term cultures

The study aims to identify the phenotypic marker expressions of different human adult stem cells derived from, namely, bone marrow, subcutaneous fat, and omentum fat, cultured in different media, namely, DMEM-Low Glucose, Alpha-MEM, DMEM-F12 and DMEM-KO and under long term culture conditions (>P20). We characterized immunophenotype by using various hematopoietic, mesenchymal, endothelial markers, and cell adhesion molecules in the long term cultures (Passages-P1, P3, P5, P9, P12, P15, and P20.) Interestingly, data revealed similar marker expression profiles irrespective of source, basal media, and extensive culturing. This demonstrates that all adult stem cell sources mentioned in this study share similar phenotypic marker and all media seem appropriate for culturing these sources. However, a disparity was observed in the markers such as CD49d, CD54, CD117, CD29, and CD106, thereby warranting further research on these markers. Besides the aforesaid objective, it is understood from the study that immunophenotyping acts as a valuable tool to identify inherent property of each cell, thereby leading to a valuable cell based therapy.

Subcutaneous Adipose Tissue-Derived Stem Cell Utility Is Independent of Anatomical Harvest Site

One of the challenges for tissue engineering and regenerative medicine is to obtain suitably large cell numbers for therapy. Mesenchymal stem cells (MSCs) can easily be expanded in vitro to obtain large numbers of cells, but this approach may induce cellular senescence. The characteristics of cells are dependent on variables like age, body mass index (BMI), and disease conditions, however, and in the case of adipose tissue-derived stem cells (ASCs), anatomical harvest site is also an important variable that can affect the regenerative potential of isolated cells. We therefore had kept the parameters (age, BMI, disease conditions) constant in this study to specifically assess influence of anatomical sites of individual donors on utility of ASCs. Adipose tissue was obtained from multiple anatomical sites in individual donors, and viability and nucleated cell yield were determined. MSC frequency was enumerated using colony forming unit assay and cells were characterized by flow cytometry. Growth characteristics were determined by long-term population doubling analysis of each sample. Finally, MSCs were induced to undergo adipogenic, osteogenic, and chondrogenic differentiation. To validate the findings, these results were compared with similar single harvest sites from multiple individual patients. The results of the current study indicated that MSCs obtained from multiple harvest sites in a single donor have similar morphology and phenotype. All adipose depots in a single donor exhibited similar MSC yield, viability, frequency, and growth characteristics. Equivalent differentiation capacity into osteocytes, adipocytes, and chondrocytes was also observed. On the basis of results, we conclude that it is acceptable to combine MSCs obtained from various anatomical locations in a single donor to obtain suitably large cell numbers required for therapy, avoiding in vitro senescence and lengthy and expensive in vitro culturing and expansion steps.

Negative energy balance induced by paradoxical sleep deprivation causes multicompartmental changes in adipose tissue and skeletal muscle

Objective. Describe multicompartmental changes in the fat and various muscle fiber types, as well as the hormonal profile and metabolic rate induced by SD in rats. Methods. Twenty adult male Wistar rats were equally distributed into two groups: experimental group (EG) and control group (CG). The EG was submitted to SD for 96 h. Blood levels of corticosterone (CORT), total testosterone (TESTO), insulin like growth factor-1 (IGF-1), and thyroid hormones (T3 and T4) were used to assess the catabolic environment. Muscle trophism was measured using a cross-sectional area of various muscles (glycolytic, mixed, and oxidative), and lipolysis was inferred by the weight of fat depots from various locations, such as subcutaneous, retroperitoneal, and epididymal. The metabolic rate was measured using oxygen consumption ([Formula: see text]O2) measurement. Results. SD increased CORT levels and decreased TESTO, IGF-1, and T4. All fat depots were reduced in weight after SD. Glycolytic and mixed muscles showed atrophy, whereas atrophy was not observed in oxidative muscle. Conclusion. Our data suggest that glycolytic muscle fibers are more sensitive to atrophy than oxidative fibers during SD and that fat depots are reduced regardless of their location.

Adipokines: a link between obesity and dementia?

Being overweight or obese, as measured with body-mass index or central adiposity (waist circumference), and the trajectory of body-mass index over the life course have been associated with brain atrophy, white matter changes, disturbances of blood-brain barrier integrity, and risk of all-cause late-onset dementia and Alzheimer's disease. This observation leads us to question what it is about body-mass index that is associated with health of the brain and dementia risk. If high body-mass index and central adiposity represent an increase in adipose tissue, then the endocrine function of adipose tissue, mediated by adipose tissue hormones and adipokines, could be a clue to mechanisms that underlie the association with dementia and Alzheimer's disease. Hundreds of adipokines have been identified, creating a complexity that is a challenge to simplify. Nonetheless, adipokines are being investigated in association with clinical dementia outcomes, and with imaging-based measures of brain volume, structure, and function in human beings and in preclinical models of clinical dementia.

Preliminary study on electrophysiological changes after cellular autograft in age-related macular degeneration

Evolving atrophic macular degeneration represents at least 80% of all macular degenerations and is currently without a standardized care. Autologous fat transplantation efficacy was demonstrated by several studies, as these cells are able to produce growth factors. The aim of the work was to demonstrate possible therapeutic effect of the joined suprachoroidal graft of adipocytes, adipose-derived stem cells (ADSCs) in stromal vascular fractions (SVFs) of adipose tissue, and platelet-rich plasma (PRP). Twelve eyes in 12 dry age-related macular degeneration (AMD) patients, aged 71.25 (SD ± 6.8) between 62 and 80 years, were analyzed. A complete ocular evaluation was performed using best corrected visual acuity (BCVA), retinographic analysis, spectral-domain optical coherence tomography, microperimetry, computerized visual field, and standard electroretinogram (ERG). Each eye received a cell in graft between choroid and sclera of mature fat cells and ADSCs in SVF enriched with PRP by means of the variant second Limoli (Limoli retinal restoration technique [LRRT]). In order to test if the differences pre- and post-treatment were significant, the Wilcoxon signed-rank test has been performed. Adverse effects were not reported in the patients. After surgery with LRRT, the most significant increase in the ERG values was recorded by scotopic rod-ERG (answer coming from the rods), from 41.26 to 60.83 μV with an average increase of 47.44% highly significant (P < 0.05). Moderately significant was the one recorded by scotopic maximal ERG (answer coming from the rods and cones), from 112.22 to 129.68 μV with an average increase of 15.56% (P < 0.1). Cell-mediated therapy based on growth factors used appears interesting because it can improve the retinal functionality responses in the short term. The ERG could, therefore, be used to monitor the effect of cell-mediated regenerative therapies.

Detection of 11 beta-hydroxysteroid dehydrogenase type 1, the glucocorticoid and mineralocorticoid receptor in various adipose tissue depots of dairy cows supplemented with conjugated linoleic acids

Early lactating cows mobilize adipose tissue (AT) to provide energy for milk yield and maintenance and are susceptible to metabolic disorders and impaired immune response. Conjugated linoleic acids (CLA), mainly the trans-10, cis-12 isomer, reduce milk fat synthesis and may attenuate negative energy balance. Circulating glucocorticoids (GC) are increased during parturition in dairy cows and mediate differentiating and anti-inflammatory effects via glucocorticoid (GR) and mineralocorticoid receptors (MR) in the presence of the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1). Activated GC are the main ligands for both receptors in AT; therefore, we hypothesized that tissue-specific GC metabolism is effected by varying amounts of GR, MR and 11βHSD1 and/or their localization within AT depots. Furthermore, the lipolytic and antilipogenic effects of CLA might influence the GC/GR/MR system in AT. Therefore, we aimed to localize GR and MR as well as the expression pattern and activity of 11βHSD1 in different AT depots during early lactation in dairy cows and to identify potential effects of CLA. Primiparous German Holstein cows were divided into a control (CON) and a CLA group. From day 1 post-partum (p.p.) until sample collection, the CLA group was fed with 100 g/d CLA (contains 10 g each of the cis-9, trans-11 and the trans-10, cis-12-CLA isomers). CON cows (n = 5 each) were slaughtered on day 1, 42 and 105 p.p., while CLA cows (n = 5 each) were slaughtered on day 42 and 105 p.p. Subcutaneous fat from tailhead, withers and sternum, and visceral fat from omental, mesenteric and retroperitoneal depots were sampled. The localization of GR and 11βHSD1 in mature adipocytes - being already differentiated - indicates that GC promote other effects via GR than differentiation. Moreover, MR were observed in the stromal vascular cell fraction and positively related to the pre-adipocyte marker Pref-1. However, only marginal CLA effects were observed in this study.

Isolation, characterization, differentiation, and application of adipose-derived stem cells

While bone marrow-derived mesenchymal stem cells are known and have been investigated for a long time, mesenchymal stem cells derived from the adipose tissue were identified as such by Zuk et al. in 2001. However, as subcutaneous fat tissue is a rich source which is much more easily accessible than bone marrow and thus can be reached by less invasive procedures, adipose-derived stem cells have moved into the research spotlight over the last 8 years.Isolation of stromal cell fractions involves centrifugation, digestion, and filtration, resulting in an adherent cell population containing mesenchymal stem cells; these can be subdivided by cell sorting and cultured under common conditions.They seem to have comparable properties to bone marrow-derived mesenchymal stem cells in their differentiation abilities as well as a favorable angiogenic and anti-inflammatory cytokine secretion profile and therefore have become widely used in tissue engineering and clinical regenerative medicine.

c-Kit identifies a subpopulation of mesenchymal stem cells in adipose tissue with higher telomerase expression and differentiation potential

The stromal vascular fraction (SVF) of adipose tissue is an easy to obtain source of adipose tissue-derived stem cells (ADSCs). We and others have achieved significant but suboptimal therapeutic effects with ADSCs in various settings, mainly due to low rates of differentiation into specific cell types and with the downside of undesired side effects as a consequence of the undifferentiated ADSCs. These data prompted us to find new stem cell-specific markers for ADSCs and/or subpopulations with higher differentiation potential to specific lineages. We found a subpopulation of human ADSCs, marked by c-Kit positiveness, resides in a perivascular location, and shows higher proliferative activity and self-renewal capacity, higher telomerase activity and expression, higher in vitro adipogenic efficiency, a higher capacity for the maintenance of cardiac progenitors, and higher pancreatogenic and hepatogenic efficiency independently of CD105 expression. Our data suggests that the isolation of ADSC subpopulations with anti-c-Kit antibodies allows for the selection of a more homogeneous subpopulation with increased cardioprotective properties and increased adipogenic and endodermal differentiation potential, providing a useful tool for specific therapies in regenerative medicine applications.

Recruitment of fat cell precursors during high fat diet in C57BL/6J mice is fat depot specific

OBJECTIVE

The study aims to explore long-term dietary effects on increases in body mass and fat depot enlargement through the recruitment of early in life labeled progenitor cells to the adipolineage.

METHODS

Neonate male C57BL/6J (B6) mice were injected intraperitoneally with BrdU. From 4 until 30 weeks of age they were fed either low fat diet (LFD) or high fat diet (HFD). BrdU-labeled cells were analyzed by flow cytometric and immunohistochemical assays after 10 days and 4, 8, 16, and 30 weeks.

RESULTS

Mice fed HFD were heavier than mice fed LFD with the most dramatic disparity recorded between week 16 and 30. BrdU-bearing cells showed the decrease in the percentage content of labeled cells in inguinal (iWAT), epididymal (eWAT) and bone marrow (BM) tissues, regardless diets. However, iWAT collected from animals on HFD showed significant increase in labeled-cells at week 16th, which coincides with robust increase in inguinal but not epididymal fat weight between 16 and 30 weeks age.

CONCLUSIONS

Cells labeled with BrdU during neonate life of B6 mice persist in fat tissues for long period of time and are recruited to the adipocyte lineage in a favorable (obesogenic) environment in iWAT but not in eWAT.

Adipocyte lineages: tracing back the origins of fat

The obesity epidemic has intensified efforts to understand the mechanisms controlling adipose tissue development. Adipose tissue is generally classified as white adipose tissue (WAT), the major energy storing tissue, or brown adipose tissue (BAT), which mediates non-shivering thermogenesis. It is hypothesized that brite adipocytes (brown in white) may represent a third adipocyte class. The recent realization that brown fat exist in adult humans suggests increasing brown fat energy expenditure could be a therapeutic strategy to combat obesity. To understand adipose tissue development, several groups are tracing the origins of mature adipocytes back to their adult precursor and embryonic ancestors. From these studies emerged a model that brown adipocytes originate from a precursor shared with skeletal muscle that expresses Myf5-Cre, while all white adipocytes originate from a Myf5-negative precursors. While this provided a rational explanation to why BAT is more metabolically favorable than WAT, recent work indicates the situation is more complex because subsets of white adipocytes also arise from Myf5-Cre expressing precursors. Lineage tracing studies further suggest that the vasculature may provide a niche supporting both brown and white adipocyte progenitors; however, the identity of the adipocyte progenitor cell is under debate. Differences in origin between adipocytes could explain metabolic heterogeneity between depots and/or influence body fat patterning particularly in lipodystrophy disorders. Here, we discuss recent insights into adipose tissue origins highlighting lineage-tracing studies in mice, how variations in metabolism or signaling between lineages could affect body fat distribution, and the questions that remain unresolved. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

Adipose tissue-derived mesenchymal stem cells: isolation, expansion, and characterization

Over the last decade, cell therapy has emerged as a potentially new approach for the treatment of cardiovascular diseases. Among the wide range of cell types and sources, adipose-derived mesenchymal stem cells have shown promise, mainly due to its plasticity and remarkable paracrine-secretion capacity, largely demonstrated at the in vitro and in vivo levels. Furthermore, its accessibility and abundance, the low morbidity of the surgical procedure, its easy isolation, culture, and long-term passaging capacity added to its immunomodulatory properties that could allow its allogeneic transplantation, making it one of the most attractive candidates for clinical application. In this chapter, we will focus on the methodology for the isolation, expansion, phenotypical characterization, differentiation, and storage of the adipose-derived stem cells.

Stromal Vascular Cells and Adipogenesis: Cells within Adipose Depots Regulate Adipogenesis

A collection of investigations indicate the importance of adipose tissue stromal/stem cells to vasculogenesis and angiogenesis during adipogenesis. Early in development the stromal-vascular (S-V) elements control and dictate the extent of adipogenesis. For instance, the vasculature and connective tissue collagen matrix develops before overt adipocyte differentiation. Definitive studies of human adipose tissue stem cells (ADSC) provided an understanding of stem cell identity and function. In this regard, a novel vascular stem cell theory proposes that ADSC are a mixed population of vascular stem cells (VSC) with differential potential proportional to the angiogenic potential of the vasculature. The differential potential of VSC can range considerably in a continuous fashion and can include vascular smooth cells, endothelial cells (EC) and adipocytes. These observations are consistent with fetal adipose tissue studies that show location-dependent angiogenic potential ranging from more to less in regards to a predominant presence of EC and developing arterioles before overt adipogenesis.

Cell supermarket: adipose tissue as a source of stem cells

Adipose tissue is derived from numerous sources, and in recent years this tissue has been shown to provide numerous cells from what seemingly was a population of homogeneous adipocytes. Considering the types of cells that adipose tissue-derived cells may form, these cells may be useful in a variety of clinical and scientific applications. The focus of this paper is to reflect on this area of research and to provide a list of potential (future) research areas.

Adipose-derived mesenchymal cells for bone regereneration: state of the art

Adipose tissue represents a hot topic in regenerative medicine because of the tissue source abundance, the relatively easy retrieval, and the inherent biological properties of mesenchymal stem cells residing in its stroma. Adipose-derived mesenchymal stem cells (ASCs) are indeed multipotent somatic stem cells exhibiting growth kinetics and plasticity, proved to induce efficient tissue regeneration in several biomedical applications. A defined consensus for their isolation, classification, and characterization has been very recently achieved. In particular, bone tissue reconstruction and regeneration based on ASCs has emerged as a promising approach to restore structure and function of bone compromised by injury or disease. ASCs have been used in combination with osteoinductive biomaterial and/or osteogenic molecules, in either static or dynamic culture systems, to improve bone regeneration in several animal models. To date, few clinical trials on ASC-based bone reconstruction have been concluded and proved effective. The aim of this review is to dissect the state of the art on ASC use in bone regenerative applications in the attempt to provide a comprehensive coverage of the topics, from the basic laboratory to recent clinical applications.

Transplantation of modified human adipose derived stromal cells expressing VEGF165 results in more efficient angiogenic response in ischemic skeletal muscle

Background

Modified cell-based angiogenic therapy has become a promising novel strategy for ischemic heart and limb diseases. Most studies focused on myoblast, endothelial cell progenitors or bone marrow mesenchymal stromal cells transplantation. Yet adipose-derived stromal cells (in contrast to bone marrow) are abundantly available and can be easily harvested during surgery or liposuction. Due to high paracrine activity and availability ADSCs appear to be a preferable cell type for cardiovascular therapy. Still neither genetic modification of human ADSC nor in vivo therapeutic potential of modified ADSC have been thoroughly studied. Presented work is sought to evaluate angiogenic efficacy of modified ADSCs transplantation to ischemic tissue.

Materials and methods

Human ADSCs were transduced using recombinant adeno-associated virus (rAAV) serotype 2 encoding human VEGF165. The influence of genetic modification on functional properties of ADSCs and their angiogenic potential in animal models were studied.

Results

We obtained AAV-modified ADSC with substantially increased secretion of VEGF (VEGF-ADSCs). Transduced ADSCs retained their adipogenic and osteogenic differentiation capacities and adhesion properties. The level of angiopoetin-1 mRNA was significantly increased in VEGF-ADSC compared to unmodified cells yet expression of FGF-2, HGF and urokinase did not change. Using matrigel implant model in mice it was shown that VEGF-ADSC substantially stimulated implant vascularization with paralleling increase of capillaries and arterioles. In murine hind limb ischemia test we found significant reperfusion and revascularization after intramuscular transplantation of VEGF-ADSC compared to controls with no evidence of angioma formation.

Conclusions

Transplantation of AAV-VEGF- gene modified hADSC resulted in stronger therapeutic effects in the ischemic skeletal muscle and may be a promising clinical treatment for therapeutic angiogenesis.

Mechanisms and metabolic implications of regional differences among fat depots

Fat distribution is closely linked to metabolic disease risk. Distribution varies with sex, genetic background, disease state, certain drugs and hormones, development, and aging. Preadipocyte replication and differentiation, developmental gene expression, susceptibility to apoptosis and cellular senescence, vascularity, inflammatory cell infiltration, and adipokine secretion vary among depots, as do fatty-acid handling and mechanisms of enlargement with positive-energy and loss with negative-energy balance. How interdepot differences in these molecular, cellular, and pathophysiological properties are related is incompletely understood. Whether fat redistribution causes metabolic disease or whether it is a marker of underlying processes that are primarily responsible is an open question.

Lineage depletion of stromal vascular fractions isolated from human adipose tissue: a novel approach towards cell enrichment technology

The therapeutic rationale for tissue repair and regeneration using stem cells is at its infancy and needs advancement in understanding the role of individual component's innate capability. As stem cells of adipose tissue reside in a more heterogeneous population of stromal vascular fractions, cell separation or sorting becomes an eminent step towards revealing their unique properties. This study elucidates the comparative efficacy of lineage depleted adipose derived stromal vascular fraction (SVF) and their innate ability using magnetic activated cell sorter (MACS). To this end, isolated SVF from human adipose tissue was lineage depleted according to the manufacturer's instructions using specific antibody cocktail through MACS. The enriched lineage negative (lin-) and lineage positive (lin+) cell fractions were cultured, phenotypically characterized for the panel of cell surface markers using flowcytometry and subjected to osteoblastic and adipogenic differentiation. The expression profile obtained for lin- cells was CD34-/CD45-/HLADR-/CD49d-/CD140b-/CD31-/CD90+/CD105+/CD73+/CD54+/CD166+/CD117- when compared to Lin+ cells expressing CD34+/CD45+/HLADR-/CD49d-/CD140b+/CD31-/CD90+/CD105+/CD73+/CD54+/CD166+/CD117+ (CD-cluster of differentiation). These results, thus, advances our understanding on the inherent property of the individual cell population. Furthermore, both the fractions exhibited mesodermal lineage differentiation capacity. To conclude, this research pursuit rationalized the regenerative therapeutic applicability of both lin- and lin+ cultures of human adipose tissue for disorders of mesodermal, haematological and vascular origin.

Adipose-Derived Stem Cells: Isolation, Characterization, and Differentiation Potential

In mammals, the two main types of adipose tissues, white and brown adipose tissues, exert different physiological functions. White adipose tissue (WAT) is for storing energy, while brown adipose tissue (BAT) is for energy consumption. Adipose-derived stem cells (ADSCs) are abundant in WAT and BAT, have multipotent characteristics, and are easily extracted. ADSCs can be differentiated into several cell lineages, including adipocytes, osteoblasts, chondrocytes (cartilage cells), myocytes, and neuronal cells. Therefore, ADSC could be considered as a strategy for future regenerative medicine and tissue engineering.

Adipose-derived mesenchymal stem cells and regenerative medicine

Adipose tissue-derived mesenchymal stem cells (ADSCs) are multipotent and can differentiate into various cell types, including osteocytes, adipocytes, neural cells, vascular endothelial cells, cardiomyocytes, pancreatic β-cells, and hepatocytes. Compared with the extraction of other stem cells such as bone marrow-derived mesenchymal stem cells (BMSCs), that of ADSCs requires minimally invasive techniques. In the field of regenerative medicine, the use of autologous cells is preferable to embryonic stem cells or induced pluripotent stem cells. Therefore, ADSCs are a useful resource for drug screening and regenerative medicine. Here we present the methods and mechanisms underlying the induction of multilineage cells from ADSCs.

Plac8 is required for white adipocyte differentiation in vitro and cell number control in vivo

Plac8 belongs to an evolutionary conserved family of proteins, mostly abundant in plants where they control fruit weight through regulation of cell number. In mice, Plac8 is expressed both in white and brown adipose tissues and we previously showed that Plac8^−/− mice develop late-onset obesity, with abnormal brown fat differentiation and reduced thermogenic capacity. We also showed that in brown adipocytes, Plac8 is an upstream regulator of C/EBPβ expression. Here, we first assessed the role of Plac8 in white adipogenesis in vitro. We show that Plac8 is induced early after induction of 3T3-L1 adipocytes differentiation, a process that is prevented by Plac8 knockdown; similarly, embryonic fibroblasts obtained from Plac8 knockout mice failed to form adipocytes upon stimulation of differentiation. Knockdown of Plac8 in 3T3-L1 was associated with reduced expression of C/EBPβ, Krox20, and Klf4, early regulators of the white adipogenic program, and we show that Plac8 could transactivate the C/EBPβ promoter. In vivo, we show that absence of Plac8 led to increased white fat mass with enlarged adipocytes but reduced total number of adipocytes. Finally, even though Plac8^−/− mice showed impaired thermogenesis due to brown fat dysfunction, this was not associated with changes in glycemia or plasma free fatty acid and triglyceride levels. Collectively, these data indicate that Plac8 is an upstream regulator of C/EBPβ required for adipogenesis in vitro. However, in vivo, Plac8 is dispensable for the differentiation of white adipocytes with preserved fat storage capacity but is required for normal fat cell number regulation.

Losartan Improves Adipose Tissue-Derived Stem Cell Niche by Inhibiting Transforming Growth Factor-β and Fibrosis in Skeletal Muscle Injury

Recently, adipose tissue-derived stem cells (ASCs) were emerged as an alternative, abundant, and easily accessible source of stem cell therapy. Previous studies revealed losartan (an angiotensin II type I receptor blocker) treatment promoted the healing of skeletal muscle by attenuation of the TGF-β signaling pathway, which inhibits muscle differentiation. Therefore, we hypothesized that a combined therapy using ASCs and losartan might dramatically improve the muscle remodeling after muscle injury. To determine the combined effect of losartan with ASC transplantation, we created a muscle laceration mouse model. EGFP-labeled ASCs were locally transplanted to the injured gastrocnemius muscle after muscle laceration. The dramatic muscle regeneration and the remarkably inhibited muscular fibrosis were observed by combined treatment. Transplanted ASCs fused with the injured or differentiating myofibers. Myotube formation was also enhanced by ASC+ satellite coculture and losartan treatment. Thus, the present study indicated that ASC transplantation effect for skeletal muscle injury can be dramatically improved by losartan treatment inducing better niche.

Human adipose tissue-derived SSEA-4 subpopulation multi-differentiation potential towards the endothelial and osteogenic lineages

Human adipose tissue has been recently recognized as a potential source of stem cells for regenerative medicine applications, including bone tissue engineering (TE). Despite the gathered knowledge regarding the differentiation potential of human adipose tissue-derived stem cells (hASCs), in what concerns the endothelial lineage many uncertainties are still present. The existence of a cell subpopulation within the human adipose tissue that expresses a SSEA-4 marker, usually associated to pluripotency, raises expectations on the differentiation capacity of these cells (SSEA-4(+)hASCs). In the present study, the endothelial and osteogenic differentiation potential of the SSEA-4(+)hASCs was analyzed, aiming at proposing a single-cell source/subpopulation for the development of vascularized bone TE constructs. SSEA-4(+)hASCs were isolated using immunomagnetic sorting and cultured either in α-MEM, in EGM-2 MV (endothelial growth medium), or in osteogenic medium. SSEA-4(+)hASCs cultured in EGM-2 MV formed endothelial cell-like colonies characterized by a cobblestone morphology and expression of CD31, CD34, CD105, and von Willebrand factor as determined by quantitative reverse transcriptase (RT)-polymerase chain reaction, immunofluorescence, and flow cytometry. The endothelial phenotype was also confirmed by their ability to incorporate acetylated low-density lipoprotein and to form capillary-like structures when seeded on Matrigel. SSEA-4(+)hASCs cultured in α-MEM displayed fibroblastic-like morphology and exhibited a mesenchymal surface marker profile (>90% CD90(+)/CD73(+)/CD105(+)). After culture in osteogenic conditions, an overexpression of osteogenic-related markers (osteopontin and osteocalcin) was observed both at molecular and protein levels. Matrix mineralization detected by Alizarin Red staining confirmed SSEA-4(+)hASCs osteogenic differentiation. Herein, we demonstrate that from a single-cell source, human adipose tissue, and by selecting the appropriate subpopulation it is possible to obtain microvascular-like endothelial cells and osteoblasts, the most relevant cell types for the creation of vascularized bone tissue-engineered constructs.

Breast reconstruction with autologous fat graft mixed with platelet-rich plasma

BACKGROUND

The purpose of this study was to review the authors' experience of fat grafting, evaluating the effects related to the use of fat grafting with platelet-rich plasma (PRP) in the improvement of fat volume in breast reconstruction and comparing the results with a control group (only centrifuged fat grafting).

METHODS

A total of 50 patients aged between 19 and 60 years affected by breast soft-tissue defects were analyzed at the Plastic and Reconstructive Department of the University of Tor Vergata. They were treated with fat grafting + PRP. The control group (50 patients with breast soft-tissue defects) were treated with centrifuged fat grafting injection according to Coleman's procedure.

RESULTS

The patients treated with PRP added to the autologous fat grafts showed a 69% maintenance of the contour restoring and of 3-dimensional volume after 1 year, whereas the patients of the control group treated with centrifuged fat grafting showed a 39% maintenance.

CONCLUSION

PRP mixed with fat grafting leads to an improvement in maintaining breast volume in patients affected by breast soft-tissue defects.

Concise review: therapeutic potential of adipose tissue-derived angiogenic cells

Inadequate blood supply to tissues is a leading cause of morbidity and mortality today. Ischemic symptoms caused by obstruction of arterioles and capillaries are currently not treatable by vessel replacement or dilatation procedures. Therapeutic angiogenesis, the treatment of tissue ischemia by promoting the proliferation of new blood vessels, has recently emerged as one of the most promising therapies. Neovascularization is most often attempted by introduction of angiogenic cells from different sources. Emerging evidence suggests that adipose tissue (AT) is an excellent reservoir of autologous cells with angiogenic potential. AT yields two cell populations of importance for neovascularization: AT-derived mesenchymal stromal cells, which likely act predominantly as pericytes, and AT-derived endothelial cells (ECs). In this concise review we discuss different physiological aspects of neovascularization, briefly present cells isolated from the blood and bone marrow with EC properties, and then discuss isolation and cell culture strategies, phenotype, functional capabilities, and possible therapeutic applications of angiogenic cells obtained from AT.

Concise review: Adipose-derived stem cells as a novel tool for future regenerative medicine

The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs offers a paradigm shift that may provide alternative therapeutic solutions for a number of diseases. The use of either embryonic stem cells (ESCs) or induced pluripotent stem cells in clinical situations is limited due to cell regulations and to technical and ethical considerations involved in the genetic manipulation of human ESCs, even though these cells are, theoretically, highly beneficial. Mesenchymal stem cells seem to be an ideal population of stem cells for practical regenerative medicine, because they are not subjected to the same restrictions. In particular, large number of adipose-derived stem cells (ASCs) can be easily harvested from adipose tissue. Furthermore, recent basic research and preclinical studies have revealed that the use of ASCs in regenerative medicine is not limited to mesodermal tissue but extends to both ectodermal and endodermal tissues and organs, although ASCs originate from mesodermal lineages. Based on this background knowledge, the primary purpose of this concise review is to summarize and describe the underlying biology of ASCs and their proliferation and differentiation capacities, together with current preclinical and clinical data from a variety of medical fields regarding the use of ASCs in regenerative medicine. In addition, future directions for ASCs in terms of cell-based therapies and regenerative medicine are discussed.

Development of a vascularized skin construct using adipose-derived stem cells from debrided burned skin

Large body surface area burns pose significant therapeutic challenges. Clinically, the extent and depth of burn injury may mandate the use of allograft for temporary wound coverage while autografts are serially harvested from the same donor areas. The paucity of donor sites in patients with burns involving large surface areas highlights the need for better skin substitutes that can achieve early and complete coverage and retain normal skin durability with minimal donor requirements. We have isolated autologous stem cells from the adipose layer of surgically debrided burned skin (dsASCs), using a point-of-care stem cell isolation device. These cells, in a collagen—polyethylene glycol fibrin-based bilayer hydrogel, differentiate into an epithelial layer, a vascularized dermal layer, and a hypodermal layer. All-trans-retinoic acid and fenofibrate were used to differentiate dsASCs into epithelial-like cells. Immunocytochemical analysis showed a matrix- and time-dependent change in the expression of stromal, vascular, and epithelial cell markers. These results indicate that stem cells isolated from debrided skin can be used as a single autologous cell source to develop a vascularized skin construct without culture expansion or addition of exogenous growth factors. This technique may provide an alternative approach for cutaneous coverage after extensive burn injuries.

Intrinsic differences in adipocyte precursor cells from different white fat depots

Obesity and body fat distribution are important risk factors for the development of type 2 diabetes and metabolic syndrome. Evidence has accumulated that this risk is related to intrinsic differences in behavior of adipocytes in different fat depots. In the current study, we demonstrate that adipocyte precursor cells (APCs) isolated from visceral and subcutaneous white adipose depots of mice have distinct patterns of gene expression, differentiation potential, and response to environmental and genetic influences. APCs derived from subcutaneous fat differentiate well in the presence of classical induction cocktail, whereas those from visceral fat differentiate poorly but can be induced to differentiate by addition of bone morphogenetic protein (BMP)-2 or BMP-4. This difference correlates with major differences in gene expression signature between subcutaneous and visceral APCs. The number of APCs is higher in obesity-prone C57BL/6 mice than obesity-resistant 129 mice, and the number in both depots is increased by up to 270% by exposure of mice to high-fat diet. Thus, APCs from visceral and subcutaneous depots are dynamic populations, which have intrinsic differences in gene expression, differentiation properties, and responses to environmental/genetic factors. Regulation of these populations may provide a new target for the treatment and prevention of obesity and its metabolic complications.

Centrifugal countercurrent chromatography to elucidate surface differences of adipose tissue-derived stem cells

The current methods of isolation of adipose tissue-derived stem cells result in a heterogeneous population that might interfere with their differentiation potential and makes it difficult to compare the results between different groups. Partition in aqueous two-phase systems is one of the few techniques that separate cells on the basis of surface properties, gentle enough to isolate fragile cell types in isotonic conditions without altering their structure, and can be easily scaled. In this study, stem cells isolated from human adipose tissue seeded and expanded in vitro were fractionated by using centrifugal countercurrent distribution in an aqueous two-phase system. The separated subpopulations revealed the high heterogeneity of adipose tissue-derived stem cell samples. Comparative partition analyses showed that aging induces a loss of heterogeneity, which is not due to a loss of cell viability associated to age. The phosphatidylserine externalization, an apoptotic feature, is the main factor in cell partition that results in a decreased hydrophobicity of the cell surface. This procedure may be suitable for separating adipose tissue-derived stem cell populations enriched in some functional and/or structural surface characteristics. The possibility of a very effective separation of different subpopulations in opposite phases would be an interesting development of the method.

Intra-articular adipose-derived mesenchymal stem cells from rheumatoid arthritis patients maintain the function of chondrogenic differentiation

OBJECTIVES

To evaluate the chondrogenic potential, phenotype and percentage of IA adipose-derived mesenchymal stem cells (ADSCs) from RA patients in comparison with OA patients. The effect of TNF treatment on ADSC differentiation was also examined.

METHODS

Adipose tissue was obtained from RA and OA patients. ADSCs were isolated and cultured until passage 4. After that period, the phenotype and percentage of these cells were analysed by flow cytometry. Passage 4 cells were cultured in chondrogenic medium with or without TNF. After 3 weeks of differentiation the expression of Sox9, aggrecan (Acan) and collagen 2a (Col2a) mRNA was assessed by RT-PCR and GAG deposition by alcian blue staining.

RESULTS

The phenotype and percentage of ADSCs were similar in both RA and OA. The results of alcian blue staining showed effective chondrogenesis in RA and OA ADSCs. TNF inhibited GAG deposition in both RA and OA samples similarly. Sox9, Acan and Col2a mRNA expression was significantly increased in chondrogenic-medium-treated cells (P<0.05) and decreased after TNF exposure (P<0.01). No statistically significant differences between RA and OA were observed.

CONCLUSION

ADSCs from RA and OA patients are similar with regard to their phenotype, percentage in IA tissue and chondrogenic potential, which is reduced after exposure to TNF.