Defining stem and progenitor cells within adipose tissue

The Effects of Facial Lipografting on Skin Quality: A Systematic Review

BACKGROUND

Autologous lipografting for improvement of facial skin quality was first described by Coleman in 2006. The current dogma dictates that adipose tissue-derived stromal cells that reside in the stromal vascular fraction of lipograft contribute to skin rejuvenation (e.g., increased skin elasticity), a more homogenous skin color, and softening of skin texture. Nowadays, many studies have been reported on this "skin rejuvenation" effect of autologous fat grafting. This systematic review was undertaken to assess the efficacy of autologous lipografting on skin quality.

METHODS

The MEDLINE, Embase, Cochrane Central, Web of Science, and Google Scholar databases were searched for studies evaluating the effect of autologous lipografting on facial skin quality (May 11, 2018). Outcomes of interest were skin texture, color, and elasticity in addition to histologic outcomes and number of complications.

RESULTS

Nine studies were included, with 301 patients treated in total. No meta-analysis could be performed because of heterogeneity of the metrics and outcomes. Eight studies reported increased skin elasticity; improvement in skin texture; and a more homogeneous skin color after treatment with lipografting, cellular stromal vascular fraction, or nanofat. One study reported no increased skin elasticity after lipografting. Histologic improvement was seen after lipografting and adipose tissue-derived stromal cell injections. However, in general, the level of evidence of the included studies was low. No serious complications were reported.

CONCLUSION

Autologous facial lipografting and cellular stromal vascular fraction and adipose tissue-derived stromal cell injections hardly seem to improve facial skin quality but can be considered a safe procedure.

TGF-ß1 Induces Changes in the Energy Metabolism of White Adipose Tissue-Derived Human Adult Mesenchymal Stem/Stromal Cells In Vitro

Adipose tissue plays an active role in the regulation of the body’s energy balance. Mesenchymal stem/stromal cells from adipose tissue (adMSC) are the precursor cells for repair and adipogenesis. Since the balance of the differentiation state of adipose tissue-resident cells is associated with the development of various diseases, the examination of the regulation of proliferation and differentiation of adMSC might provide new therapeutic targets. Transforming growth factor-β1 (TGF-ß1) is synthetized by many cell types and is involved in various biological processes. Here, we investigated the effects of different concentrations of TGF-ß1 (1–10 ng/mL) on adMSC proliferation, metabolic activity, and analyzed the gene expression data obtained from DNA microarrays by bioinformatics. TGF-ß1 induced the concentration- and time-dependent increase in the cell number of adMSC with simultaneously unchanged cell cycle distributions. The basal oxygen consumption rates did not change significantly after TGF-ß1 exposure. However, glycolytic activity was significantly increased. The gene expression analysis identified 3275 differentially expressed genes upon exposure to TGF-ß1. According to the pathway enrichment analyses, they also included genes associated with energy metabolism. Thus, it was shown that TGF-ß1 induces changes in the energy metabolism of adMSC. Whether these effects are of relevance in vivo and whether they contribute to pathogenesis should be addressed in further examinations.

Resveratrol Effect on Adipose-Derived Stem Cells Differentiation to Chondrocyte in Three-Dimensional Culture

Purpose: Adipose stem cells (ASCs) are pluripotent cells with the ability of self-renewal and differentiation into different types of mesenchymal cells. As cartilage repair is difficult due to lack of blood capillary, resveratrol (Res) is a polyphenolic compound with diverse biological properties to be possibly used in this case. The aim of the present study was to investigate the effect of Res on differentiation of ASCs into chondrocyte in a three-dimensional (3D) culture model.

Methods: Subcutaneous adipose tissues were prepared and digested enzymatically, and passed through cell strainer. ASCs were harvested in the fourth passage, and divided into five groups. The control group received chondrogenic differentiation medium (CDM) while the experimental groups received CDM plus different doses of Res (1, 10, 20, and 50 µM) for 21 days. Expression of cartilage specific genes and Sirtuin1 (SIRT 1), cell viability, apoptosis and ferric reducing antioxidant power (FRAP) were detected using reverse transcription polymerase chain reaction (RT-PCR), MTT assay, TUNEL and acridine orange/ethidium bromide (AO/EB) staining. One-way ANOVA and non-parametric Mann-Whitney U test were used for data analyses.

Results: ASCs were differentiated to chondrocyte by CDM in a three-dimensional culture. 10 and 20 µM doses of Res showed the most proliferating effect on ADSCs. The SIRT 1 genes expression and FRAP level also increased significantly compared to the control group (P<0.05). Also, OD of cell increased whereas apoptosis decreased.

Conclusion: 3D culture was a suitable condition for ASCs differentiation to chondrocyte, and lower doses of Res exert proliferation effect on ASCs.

Adipose-derived stem cells contribute to cardiovascular remodeling

Obesity is an independent risk factor for cardiovascular disease. Adipose tissue was initially thought to be involved in metabolism through paracrine. Recent researches discovered mesenchymal stem cells inside adipose tissue which could differentiate into vascular lineages in vitro and in vivo, participating vascular remodeling. However, there were few researches focusing on distinct characteristics and functions of adipose-derived stem cells (ADSCs) from different regions. This is the first comprehensive review demonstrating the variances of ADSCs from the perspective of their origins.

Construction of a vascularized bladder with autologous adipose-derived stromal vascular fraction cells combined with bladder acellular matrix via tissue engineering

The formation of an effective vascular network can promote peripheral angiogenesis, ensuring an effective supply of blood, oxygen, and nutrients to an engineered bladder, which is important for bladder tissue engineering. Stromal vascular fraction cells (SVFs) promote vascularization and improve the function of injured tissues. In this study, adipose tissue-derived SVFs were introduced as an angiogenic cell source and seeded into the bladder acellular matrix (BAM) to generate a SVF-BAM complex for bladder reconstruction. The morphological regeneration and functional restoration of the engineered bladder were evaluated. In addition, we also explored the role of the Wnt5a/sFlt-1 noncanonical Wnt signaling pathway in regulating the angiogenesis of SVFs, and in maintaining the rational capability of SVFs to differentiate into vasculature in regenerated tissues. Histological assessment indicated that the SVF-BAM complex was more effective in promoting smooth muscle, vascular, and nerve regeneration than BAM alone and subsequently led to the restoration of bladder volume and bladder compliance. Moreover, exogenous Wnt5a was able to enhance angiogenesis by increasing the activity of MMP2, MMP9, and VEGFR2. Simultaneously, the expression of sFlt-1 was also increased, which enhanced the stability of the SVFs angiogenic capability. SVFs may be a potential cell source for tissue-engineered bladders. The Wnt5a/sFlt-1 pathway is involved in the regulation of autologous vascular formation by SVFs. The rational regulation of this pathway can promote neo-microvascularization in tissue-engineered bladders.

The Role of Growth Hormone in Mesenchymal Stem Cell Commitment

Growth hormone (GH) is best known for its prominent role in promoting prepubertal growth and in regulating body composition and metabolism during adulthood. In recent years, the possible role of GH in the modulation of mesenchymal stem cell (MSC) commitment has gained interest. MSCs, characterized by active self-renewal and differentiation potential, express GH receptors. In MSCs derived from different adult tissues, GH induces an inhibition of adipogenic differentiation and favors MSC differentiation towards osteogenesis. This activity of GH indicates that regulation of body composition by GH has already started in the tissue progenitor cells. These findings have fostered research on possible uses of MSCs treated with GH in those pathologies, where a lack of or delays in bone repair occur. After an overview of GH activities, this review will focus on the research that has characterized GH’s effects on MSCs and on preliminary studies on the possible application of GH in bone regenerative medicine.

Adipose stem cells in reparative goat mastitis mammary gland

Mesenchymal stem cells have been widely used in the treatment of various chronic diseases. The objective of this survey was to evaluate the therapeutic and regenerative potential of stem cells from adipose tissue (ASCs) in the milk production recovery repair of tissue injury in mastitis goats treated with antimicrobial agents prior to cell therapy. After the diagnosis of mastitis and treatment with gentamicin, eight lactating goats were selected for cellular and subsequent therapy, physical-chemical analysis of milk, ultrasonographic and histopathological examinations. The ASCs were taken from the subcutaneous fat of a young goat cultivated in vitro, marked with Qdots-655 and injected in the left mammary gland, being the right mammary gland used as the control. After 30 days the ultrasonographic and histopathological analyzes were repeated and, in the first lactation period, the physical-chemical analysis of the milk was reapeated. Before the cellular therapy, the physical-chemical quality of the milk was compromised and the ultrasonographic and histopathological analysis revealed a chronic inflammatory process and fibrous tissue. The marking of the ASCs with Qdots enabled the tracking, by fluorescence microscopy (BX41-OLYMPUS), in the mammary tissue. In the ASCs therapy, cultures showed high cellularity and characteristics favorable to preclinical studies; with the therapy the physical-chemical parameters of the milk, fat, protein, temperature and pH showed significant differences among the groups; five animals treated with ASCs reconstituted the functionality of the gland and the connective tissue reduced in quantity and inflammatory infiltrate cells. ASCs have potential for the possible regeneration of fibrous mastitis lesions in the mammary gland, however, it would be necessary to increase injection time for the histopathological analysis, since the reconstitution of the glandular acini within the assessed period was not finalized. ASCs can be used to reestablish milk production in goat with chronic mastitis repair mammary lesions, with potential to be a promising clinical alternative for animal rehabilitation for productivity.

Microenergy acoustic pulses induced myogenesis of urethral striated muscle stem/progenitor cells

Background

Stress urinary incontinence (SUI) is a common disorder with high prevalence in women across their life span, but there are no non-surgical curative options for the condition. Stem cell-based therapy, especially endogenous stem cell therapy may be a potential treatment method for SUI. The aims of this study are to identify, isolate, and assay the function of urethral striated muscle derived stem/progenitor cells (uMDSCs) and to assess uMDSC response to microenergy acoustic pulses (MAP).

Methods

Urethral striated muscle was identified utilizing 3D imaging of solvent organs (3DISCO) and immunofluorescence (IF). uMDSCs were isolated and purified from Zucker Lean (ZL) (ZUC-LEAN) (ZUC-Leprfa 186) rats, with magnetic-activated cell sorting (MACS) and pre-plating methods. The stemness and differentiation potential of the uMDSCs were measured by cell proliferation, EdU, flow cytometry, IF, and Western blot.

Results

Comparison of the cell proliferation assays between MACS and pre-plating reveals the advantage of MACS over pre-plating. In addition, the study reveals that uMDSCs form myotubes when treated with MAP.

Conclusions

The uMDSCs within female rat urethral striated muscle could be a therapeutic target of MAP in managing SUI.

Current Strategies to Enhance Adipose Stem Cell Function: An Update

Mesenchymal stem cells (MSCs) emerged as a promising therapeutic tool targeting a variety of inflammatory disorders due to their multiple remarkable properties, such as superior immunomodulatory function and tissue-regenerative capacity. Although bone marrow (BM) is a dominant source for adult MSCs, increasing evidence suggests that adipose tissue-derived stem cells (ASCs), which can be easily obtained at a relatively high yield, have potent therapeutic advantages comparable with BM-MSCs. Despite its outstanding benefits in pre-clinical settings, the practical efficacy of ASCs remains controversial since clinical trials with ASC application often resulted in unsatisfactory outcomes. To overcome this challenge, scientists established several strategies to generate highly functional ASCs beyond the naïve cells, including (1) pre-conditioning of ASCs with various stimulants such as inflammatory agents, (2) genetic manipulation of ASCs and (3) modification of culture conditions with three-dimensional (3D) aggregate formation and hypoxic culture. Also, exosomes and other extracellular vesicles secreted from ASCs can be applied directly to recapitulate the beneficial performance of ASCs. This review summarizes the current strategies to improve the therapeutic features of ASCs for successful clinical implementation.

Pericytes for Therapeutic Bone Repair

Besides seminal functions in angiogenesis and blood pressure regulation, microvascular pericytes possess a latent tissue regenerative potential that can be revealed in culture following transition into mesenchymal stem cells. Endowed with robust osteogenic potential, pericytes and other related perivascular cells extracted from adipose tissue represent a potent and abundant cell source for refined bone tissue engineering and improved cell therapies of fractures and other bone defects. The use of diverse bone formation assays in vivo, which include mouse muscle pocket osteogenesis and calvaria replenishment, rat and dog spine fusion, and rat non-union fracture healing, has confirmed the superiority of purified perivascular cells for skeletal (re)generation. As a surprising observation though, despite strong endogenous bone-forming potential, perivascular cells drive bone regeneration essentially indirectly, via recruitment by secreted factors of local osteo-progenitors.

Tumor Formation of Adult Stem Cell Transplants in Rodent Arthritic Joints

PURPOSE

While imaging matrix-associated stem cell transplants aimed for cartilage repair in a rodent arthritis model, we noticed that some transplants formed locally destructive tumors. The purpose of this study was to determine the cause for this tumor formation in order to avoid this complication for future transplants.

PROCEDURES

Adipose-derived stem cells (ADSC) isolated from subcutaneous adipose tissue were implanted into 24 osteochondral defects of the distal femur in ten athymic rats and two immunocompetent control rats. All transplants underwent serial magnetic resonance imaging (MRI) up to 6 weeks post-transplantation to monitor joint defect repair. Nine transplants showed an increasing size over time that caused local bone destruction (group 1), while 11 transplants in athymic rats (group 2) and 4 transplants in immunocompetent rats did not. We compared the ADSC implant size and growth rate on MR images, macroscopic features, histopathologic features, surface markers, and karyotypes of these presumed neoplastic transplants with non-neoplastic ADSC transplants.

RESULTS

Implants in group 1 showed a significantly increased two-dimensional area at week 2 (p = 0.0092), 4 (p = 0.003), and 6 (p = 0.0205) compared to week 0, as determined by MRI. Histopathological correlations confirmed neoplastic features in group 1 with significantly increased size, cellularity, mitoses, and cytological atypia compared to group 2. Six transplants in group 1 were identified as malignant chondrosarcomas and three transplants as fibromyxoid sarcomas. Transplants in group 2 and immunocompetent controls exhibited normal cartilage features. Both groups showed a normal ADSC phenotype; however, neoplastic ADSC demonstrated a mixed population of diploid and tetraploid cells without genetic imbalance.

CONCLUSIONS

ADSC transplants can form tumors in vivo. Preventive actions to avoid in vivo tumor formations may include karyotyping of culture-expanded ADSC before transplantation. In addition, serial imaging of ADSC transplants in vivo may enable early detection of abnormally proliferating cell transplants.

Single-Cell RNA-Sequencing and Metabolomics Analyses Reveal the Contribution of Perivascular Adipose Tissue Stem Cells to Vascular Remodeling

OBJECTIVE

Perivascular adipose tissue (PVAT) plays a vital role in maintaining vascular homeostasis. However, most studies ascribed the function of PVAT in vascular remodeling to adipokines secreted by the perivascular adipocytes. Whether mesenchymal stem cells exist in PVAT and play a role in vascular regeneration remain unknown. Approach and Results: Single-cell RNA-sequencing allowed direct visualization of the heterogeneous PVAT-derived mesenchymal stem cells (PV-ADSCs) at a high resolution and revealed 2 distinct subpopulations, among which one featured signaling pathways crucial for smooth muscle differentiation. Pseudotime analysis of cultured PV-ADSCs unraveled their smooth muscle differentiation trajectory. Transplantation of cultured PV-ADSCs in mouse vein graft model suggested the contribution of PV-ADSCs to vascular remodeling through smooth muscle differentiation. Mechanistically, treatment with TGF-β1 (transforming growth factor β1) and transfection of microRNA (miR)-378a-3p mimics induced a similar metabolic reprogramming of PV-ADSCs, including upregulated mitochondrial potential and altered lipid levels, such as increased cholesterol and promoted smooth muscle differentiation.

CONCLUSIONS

Single-cell RNA-sequencing allows direct visualization of PV-ADSC heterogeneity at a single-cell level and uncovers 2 subpopulations with distinct signature genes and signaling pathways. The function of PVAT in vascular regeneration is partly attributed to PV-ADSCs and their differentiation towards smooth muscle lineage. Mechanistic study presents miR-378a-3p which is a potent regulator of metabolic reprogramming as a potential therapeutic target for vascular regeneration.

Noggin depletion in adipocytes promotes obesity in mice

OBJECTIVE

Obesity has increased to pandemic levels and enhanced understanding of adipose regulation is required for new treatment strategies. Although bone morphogenetic proteins (BMPs) influence adipogenesis, the effect of BMP antagonists such as Noggin is largely unknown. The aim of the study was to define the role of Noggin, an extracellular BMP inhibitor, in adipogenesis.

METHODS

We generated adipose-derived progenitor cells and a mouse model with adipocyte-specific Noggin deletion using the AdiponectinCre transgenic mouse, and determined the adipose phenotype of Noggin-deficiency.

RESULTS

Our studies showed that Noggin is expressed in progenitor cells but declines in adipocytes, possibly allowing for lipid accumulation. Correspondingly, adipocyte-specific Noggin deletion in vivo promoted age-related obesity in both genders with no change in food intake. Although the loss of Noggin caused white adipose tissue hypertrophy, and whitening and impaired function in brown adipose tissue in both genders, there were clear gender differences with the females being most affected. The females had suppressed expression of brown adipose markers and thermogenic genes including peroxisome proliferator activated receptor gamma coactivator 1 alpha (PGC1alpha) and uncoupling protein 1 (UCP1) as well as genes associated with adipogenesis and lipid metabolism. The males, on the other hand, had early changes in a few BAT markers and thermogenic genes, but the main changes were in the genes associated with adipogenesis and lipid metabolism. Further characterization revealed that both genders had reductions in VO2, VCO2, and RER, whereas females also had reduced heat production. Noggin was also reduced in diet-induced obesity in inbred mice consistent with the obesity phenotype of the Noggin-deficient mice.

CONCLUSIONS

BMP signaling regulates female and male adipogenesis through different metabolic pathways. Modulation of adipose tissue metabolism by select BMP antagonists may be a strategy for long-term regulation of age-related weight gain and obesity.

Human adipocytes and CD34+ cells from the stromal vascular fraction of the same adipose tissue differ in their energy metabolic enzyme configuration

Adipose tissue plays a role in energy storage and metabolic balance and is composed of different cell types. The metabolic activity of the tissue itself has been a matter of research for a long time, but comparative data about the energy metabolism of different cell types of human subcutaneous adipose tissue are sparse. Therefore, we compared the activity of major energy metabolic pathways of adipocytes and CD34⁺ cells from the stromal vascular fraction (SVF) separated from the same tissue. This CD34⁺ cell fraction is enriched with adipose tissue-derived mesenchymal progenitors, as they account for the largest proportion of CD34⁺ cells of the SVF. Adipocytes displayed significantly higher mitochondrial enzyme capacities compared to CD34⁺ SVF-cells, as shown by the higher activities of isocitrate dehydrogenase and ß-hydroxyacyl-CoA dehydrogenase. Inversely, the CD34⁺ SVF-cells showed higher capacities for cytosolic carbohydrate metabolism, represented by the activity of glycolysis and the pentose phosphate pathway. Thus, the CD34⁺ SVF-cells may ensure the provision of pentose phosphates and reduction equivalents for the replication of DNA during proliferation. The data indicate that these two cell fractions of the human adipose tissue vary in their metabolic configuration adapted to their physiological demands regarding proliferation and differentiation in vivo.

Bone marrow pericyte dysfunction in individuals with type 2 diabetes

AIMS/HYPOTHESIS

Previous studies have shown that diabetes mellitus destabilises the integrity of the microvasculature in different organs by damaging the interaction between pericytes and endothelial cells. In bone marrow, pericytes exert trophic functions on endothelial cells and haematopoietic cells through paracrine mechanisms. However, whether bone marrow pericytes are a target of diabetes-induced damage remains unknown. Here, we investigated whether type 2 diabetes can affect the abundance and function of bone marrow pericytes.

METHODS

We conducted an observational clinical study comparing the abundance and molecular/functional characteristics of CD146⁺ pericytes isolated from the bone marrow of 25 individuals without diabetes and 14 individuals with uncomplicated type 2 diabetes, referring to our Musculoskeletal Research Unit for hip reconstructive surgery.

RESULTS

Immunohistochemistry revealed that diabetes causes capillary rarefaction and compression of arteriole size in bone marrow, without changing CD146⁺ pericyte counts. These data were confirmed by flow cytometry on freshly isolated bone marrow cells. We then performed an extensive functional and molecular characterisation of immunosorted CD146⁺ pericytes. Type 2 diabetes caused a reduction in pericyte proliferation, viability, migration and capacity to support in vitro angiogenesis, while inducing apoptosis. AKT is a key regulator of the above functions and its phosphorylation state is reportedly reduced in the bone marrow endothelium of individuals with diabetes. Surprisingly, we could not find a difference in AKT phosphorylation (at either Ser473 or Thr308) in bone marrow pericytes from individuals with and without diabetes. Nonetheless, the angiocrine signalling reportedly associated with AKT was found to be significantly downregulated, with lower levels of fibroblast growth factor-2 (FGF2) and C-X-C motif chemokine ligand 12 (CXCL12), and activation of the angiogenesis inhibitor angiopoietin 2 (ANGPT2). Transfection with the adenoviral vector carrying the coding sequence for constitutively active myristoylated AKT rescued functional defects and angiocrine signalling in bone marrow pericytes from diabetic individuals. Furthermore, an ANGPT2 blocking antibody restored the capacity of pericytes to promote endothelial networking.

CONCLUSIONS/INTERPRETATION

This is the first demonstration of pericyte dysfunction in bone marrow of people with type 2 diabetes. An altered angiocrine signalling from pericytes may participate in bone marrow microvascular remodelling in individuals with diabetes.

Substance P improves MSC-mediated RPE regeneration by modulating PDGF-BB

Stem cells have regenerative potentials that can be used for the treatment of critical and incurable diseases. Age-related macular degeneration (ARMD) and diabetic retinopathy are one of the most severe retinal disorders, which are mostly attributed to impairment of retinal pigmented epithelium (RPE). Thus, restoration of RPE is the main therapeutic approach to prevent the development of ocular diseases, such as ARMD. In this study, we have investigated the role of substance P (SP) on bone marrow mesenchymal stem cell (MSC)-mediated RPE regeneration in vitro. The MSCs were primed with SP followed by the addition of conditioned medium (MSC^SP-CM) to RPE. The effects of MSC^SP-CM on RPE activity was evaluated by assessing viability, proliferation rate, and migration of RPE. Ex vivo long-term culture led to altered cellular characteristics of MSCs by weakening cell viability, cytokine secretion, and differentiation potential. The conditioned medium of early passage MSC (E-MSC^CM) enhanced the RPE viability and migration, whereas the late passage MSC (L-MSC^CM) hardly influenced the RPE activity. SP priming, however, facilitated the inductive effects of MSC, and SP effect was more distinct in the late passage than in the early passage. Moreover, it was revealed that SP could exert its effects by modulating PDGF-BB secretion in the MSCs. Taken together, these results suggested that SP could restore the therapeutic effects of MSCs on retinal diseases by elevating their proliferative and paracrine activities through PDGF-PDGFR signaling in ex vivo culture.

Effects of Insulin, Metoprolol and Deferoxamine on Fat Graft Survival

BACKGROUND

The main problem faced with fat grafting is unpredictable resorption rates. Many substances have been reported to increase the survival of fat grafts. The aim of this study was to compare the effects of insulin, metoprolol and deferoxamine on fat graft survival.

METHODS

Inguinal fat pads of male Sprague-Dawley rats were harvested and split into four parts as grafts. The grafts were placed in subcutaneous pockets in four quadrants on the back area of the rats. The insulin and metoprolol group fat grafts were incubated in regular insulin and metoprolol solutions, until they were placed. Deferoxamine and control group fat grafts were placed without incubation. After surgery, the control group fat grafts were injected with 10 doses of NaCl solution once every 3 days, and the deferoxamine group fat grafts were injected with 10 doses of deferoxamine solution once every 3 days. After a graft maturation period of 3 months, the grafts were harvested for weight measurements and histological and immunohistochemical evaluation.

RESULTS

According to the rate of perilipin staining, the metoprolol group had 30% more mature viable adipocytes than the control and insulin group fat grafts (p < 0.05 and p < 0.01, respectively). CD31 activation rates were significantly higher in the deferoxamine and insulin group than in the metoprolol group (p < 0.05). CD34 staining rates did not differ between any groups (p > 0.05).

CONCLUSIONS

In this experimental study, we have shown that there was no significantly increased fat graft survival rate seen in any drug treatment group. Low survival rates of stem cells demonstrated that the adipogenesis period ended at 3 months. Treatment of fat grafts with the selective β₁-blocker metoprolol resulted in good quality better graft take with more viable mature adipocytes. However, better viability of adipocytes did not result in increased weight of the fat graft. Studies aiming to compare the effects on fat graft survival of beta-blockers with long or short durations of action, different potencies and different receptor selectivity may be designed in the future. In addition, further studies may be performed, in which immunohistochemical markers used to assess inflammation and fibrosis are added to the study after the completion of the fat graft maturation period at the end of the first year to test the permanence of the results.

NO LEVEL ASSIGNED

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Adipose tissue-derived extracellular matrix hydrogels as a release platform for secreted paracrine factors

Fat grafting is an established clinical intervention to promote tissue repair. The role of the fat's extracellular matrix (ECM) in regeneration is largely neglected. We investigated in vitro the use of human adipose tissue‐derived ECM hydrogels as release platform for factors secreted by adipose‐derived stromal cells (ASCs). Lipoaspirates from nondiabetic and diabetic donors were decellularized. Finely powdered acellular ECM was evaluated for cell remainders and DNA content. Acellular ECM was digested, and hydrogels were formed at 37°C and their viscoelastic relaxation properties investigated. Release of ASC‐released factors from hydrogels was immune assessed, and bio‐activity was determined by fibroblast proliferation and migration and endothelial angiogenesis. Acellular ECM contained no detectable cell remainders and negligible DNA contents. Viscoelastic relaxation measurements yielded no data for diabetic‐derived hydrogels due to gel instability. Hydrogels released several ASC‐released factors concurrently in a sustained fashion. Functionally, released factors stimulated fibroblast proliferation and migration as well as angiogenesis. No difference between nondiabetic and diabetic hydrogels in release of factors was measured. Adipose ECM hydrogels incubated with released factors by ASC are a promising new therapeutic modality to promote several important wound healing‐related processes by releasing factors in a controlled way.

A promising therapeutic option for diabetic bladder dysfunction: Adipose tissue-derived stem cells pretreated by defocused low-energy shock wave

Adipose tissue-derived stem cells (ADSCs) have shown effectiveness in treating diabetic bladder dysfunction (DBD). In the present study, ADSCs pretreated by defocused low-energy shock wave (DLSW) were first used to achieve better therapeutic effect. ADSCs were treated by DLSW prior to each passage. Secretions of vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) were tested. Proliferation ability was examined by staining 5-ethynyl-2-deoxyuridine (EdU) and assessing expressions of proliferating cell nuclear antigen (PCNA) and Ki67. DBD rat model was created and subgrouped via therapeutic options of phosphate-buffered saline, ADSCs, pretreated ADSCs, and ADSCs lysate. Afterward, voiding functions were evaluated, and tissues were examined by histology. Neonatal rats received intraperitoneal injection of EdU. All rats were subgrouped and treated as narrated above. Bladder tissues were stained with EdU, Stro-1, and CD34. Results showed that shocked ADSCs were activated by secreting more VEGF and NGF, by higher EdU-retaining cells ratios, and by higher expressions of PCNA and Ki67 compared with unshocked ADSCs. Shocked ADSCs had the most effective efficacy in treating DBD by secreting the most VEGF and NGF to accelerate regenerations of revascularization and innervation. Migrations of EdU⁺ Stro-1⁺ CD34^- endogenous stem cells to bladders were enhanced by injecting ADSCs. In conclusion, ADSCs pretreated by DLSW had potent therapeutic effect in treating DBD by secreting VEGF and NGF. Recruitment of endogenous stem cells was considered as an important mechanism in this regenerative process.

The extracellular domain of epithelial cell adhesion molecule (EpCAM) enhances multipotency of mesenchymal stem cells through EGFR-LIN28-LET7 signaling

Mesenchymal stem cells (MSCs) are widely considered to be an attractive cell source for regenerative therapies, but maintaining multipotency and self-renewal in cultured MSCs is especially challenging. Hence, the development and mechanistic description of strategies that help promote multipotency in MSCs will be vital to future clinical use. Here, using an array of techniques and approaches, including cell biology, RT-quantitative PCR, immunoblotting, immunofluorescence, flow cytometry, and ChIP assays, we show that the extracellular domain of epithelial cell adhesion molecule (EpCAM) (EpEX) significantly increases the levels of pluripotency factors through a signaling cascade that includes epidermal growth factor receptor (EGFR), signal transducer and activator of transcription 3 (STAT3), and Lin-28 homolog A (LIN28) and enhances the proliferation of human bone marrow MSCs. Moreover, we found that EpEX-induced LIN28 expression reduces the expression of the microRNA LET7 and up-regulates that of the transcription factor high-mobility group AT-hook 2 (HMGA2), which activates the transcription of pluripotency factors. Surprisingly, we found that EpEX treatment also enhances osteogenesis of MSCs under differentiation conditions, as evidenced by increases in osteogenic markers, including Runt-related transcription factor 2 (RUNX2). Taken together, our results indicate that EpEX stimulates EGFR signaling and thereby context-dependently controls MSC states and activities, promoting cell proliferation and multipotency under maintenance conditions and osteogenesis under differentiation conditions.

Effects of storage culture media, temperature and duration on human adipose‑derived stem cell viability for clinical use

Adipose-derived stem cells (ADSCs) are mesenchymal stem cells that are often used in regenerative medicine. Maintaining ADSC viability is important, as this optimizes the curative effects of cell therapy. However, the optimal conditions for cell viability preservation remain unknown. The present study aimed to acquire a better protocol for ADSC storage by comparing the effects of various solutions and temperatures for ADSC preservation, in order to suggest the most effective methods of short-term ADSC preservation for clinical use. ADSCs from passage 2 were suspended in solutions comprising 0.9% NaCl, 10% human serum (HS) or 10% platelet-rich plasma (PRP). Suspended cells were maintained at 4°C or room temperature (~26°C) for 2, 4 and 6 h. The differentiation capacity, apoptosis and proliferation of ADSCs were determined by oil red O/alizarin red S staining, flow cytometry, and a cell counting kit-8 cell proliferation assay, respectively. In addition, reverse transcription-quantitative polymerase chain reaction and western blot analysis was performed. The results revealed that proliferation of ADSCs decreased with time. The optimal time for ADSC use was ~2 h, and 4 h was determined to be the latest time that ADSCs should be used. The 10% HS group had the highest survival rate, followed by the 10% PRP group; these two groups had higher survival rates than the 0.9% NaCl group (P<0.05). HS and PRP at 4°C enhanced the ADSC proliferation rate (P<0.05), although the difference between these two groups was insignificant (P>0.05). In conclusion, the optimal time to use ADSCs was <2 h, and should not exceed 4 h. It was recommended that, for the transportation and short-term storage of ADSCs during clinical use, they should be stored with 10% HS at 4°C to maintain ADSC viability. In addition, this was a cost-effective and safe method.

Impaired Adipogenesis and Dysfunctional Adipose Tissue in Human Hypertrophic Obesity

The subcutaneous adipose tissue (SAT) is the largest and best storage site for excess lipids. However, it has a limited ability to expand by recruiting and/or differentiating available precursor cells. When inadequate, this leads to a hypertrophic expansion of the cells with increased inflammation, insulin resistance, and a dysfunctional prolipolytic tissue. Epi-/genetic factors regulate SAT adipogenesis and genetic predisposition for type 2 diabetes is associated with markers of an impaired SAT adipogenesis and development of hypertrophic obesity also in nonobese individuals. We here review mechanisms for the adipose precursor cells to enter adipogenesis, emphasizing the role of bone morphogenetic protein-4 (BMP-4) and its endogenous antagonist gremlin-1, which is increased in hypertrophic SAT in humans. Gremlin-1 is a secreted and a likely important mechanism for the impaired SAT adipogenesis in hypertrophic obesity. Transiently increasing BMP-4 enhances adipogenic commitment of the precursor cells while maintained BMP-4 signaling during differentiation induces a beige/brown oxidative phenotype in both human and murine adipose cells. Adipose tissue growth and development also requires increased angiogenesis, and BMP-4, as a proangiogenic molecule, may also be an important feedback regulator of this. Hypertrophic obesity is also associated with increased lipolysis. Reduced lipid storage and increased release of FFA by hypertrophic SAT are important mechanisms for the accumulation of ectopic fat in the liver and other places promoting insulin resistance. Taken together, the limited expansion and storage capacity of SAT is a major driver of the obesity-associated metabolic complications.

Isolation of Stromal Vascular Fraction by Fractionation of Adipose Tissue

Adipose tissue-derived stromal cells (ASCs) are a promising candidates for cellular therapy in the field of regenerative medicine. ASCs are multipotent mesenchymal stem cell-like and reside in the stromal vascular fraction (SVF) of adipose tissue with the capacity to secrete a plethora of pro-regenerative growth factors. Future applications of ASCs may be restricted through (trans)national governmental policies that do not allow for use of nonhuman-derived (non-autologous) enzymes to isolate ASC. Besides, enzymatic isolation procedures are also time consuming. To overcome this issue, nonenzymatic isolation procedures to isolate ASCs or the SVF are being developed, such as the fractionation of adipose tissue procedure (FAT). This standardized procedure to isolate the stromal vascular fraction can be performed within 10-12 min. The short procedure time allows for intraoperative isolation of 1 mL of stromal vascular fraction derived from 10 mL of centrifuged adipose tissue. The stromal vascular fraction mostly contains blood vessels, extracellular matrix, and ASCs. However, based on the histological stainings an interdonor variation exists which might result in different therapeutic effects. The existing interdonor variations can be addressed by histological stainings and flow cytometry.

Augmentation of Dermal Wound Healing by Adipose Tissue-Derived Stromal Cells (ASC)

The skin is the largest organ of the human body and is the first line of defense against physical and biological damage. Thus, the skin is equipped to self-repair and regenerates after trauma. Skin regeneration after damage comprises a tightly spatial-temporally regulated process of wound healing that involves virtually all cell types in the skin. Wound healing features five partially overlapping stages: homeostasis, inflammation, proliferation, re-epithelization, and finally resolution or fibrosis. Dysreguled wound healing may resolve in dermal scarring. Adipose tissue is long known for its suppressive influence on dermal scarring. Cultured adipose tissue-derived stromal cells (ASCs) secrete a plethora of regenerative growth factors and immune mediators that influence processes during wound healing e.g., angiogenesis, modulation of inflammation and extracellular matrix remodeling. In clinical practice, ASCs are usually administered as part of fractionated adipose tissue i.e., as part of enzymatically isolated SVF (cellular SVF), mechanically isolated SVF (tissue SVF), or as lipograft. Enzymatic isolation of SVF obtained adipose tissue results in suspension of adipocyte-free cells (cSVF) that lack intact intercellular adhesions or connections to extracellular matrix (ECM). Mechanical isolation of SVF from adipose tissue destructs the parenchyma (adipocytes), which results in a tissue SVF (tSVF) with intact connections between cells, as well as matrix. To date, due to a lack of well-designed prospective randomized clinical trials, neither cSVF, tSVF, whole adipose tissue, or cultured ASCs can be indicated as the preferred preparation procedure prior to therapeutic administration. In this review, we present and discuss current literature regarding the different administration options to apply ASCs (i.e., cultured ASCs, cSVF, tSVF, and lipografting) to augment dermal wound healing, as well as the available indications for clinical efficacy.

The Adipose Stromal Vascular Fraction as a Complex Cellular Source for Tissue Engineering Applications

A major challenge in tissue engineering is the generation of sufficient volumes of viable tissue for organ transplant. The development of a stable, mature vasculature is required to sustain the metabolic and functional activities of engineered tissues. Adipose stromal vascular fraction (SVF) cells are an easily accessible, heterogeneous cell system comprised of endothelial cells, macrophages, pericytes, and various stem cell populations. Collectively, SVF has been shown to spontaneously form vessel-like networks in vitro and robust, patent, and functional vasculatures in vivo. Capitalizing on this ability, we and others have demonstrated adipose SVF's utility in generating and augmenting engineered liver, cardiac, and vascular tissues, to name a few. This review highlights the scientific origins of SVF, the use of SVF as a clinically relevant vascular source, various SVF constituents and their roles, and practical considerations associated with isolating SVF for various tissue engineering applications.

Induction of Expression of CD271 and CD34 in Mesenchymal Stromal Cells Cultured as Spheroids

Cultured mesenchymal stromal cells (MSCs) are cells that can be used for tissue engineering or cell therapies owing to their multipotency and ability to secrete immunomodulatory and trophic molecules. Several studies suggest that MSCs can become pericytes when cocultured with endothelial cells (ECs) but failed to use pericyte markers not already expressed by MSCs. We hypothesized ECs could instruct MSCs to express the molecules CD271 or CD34, which are expressed by pericytes in situ but not by MSCs. CD271 is a marker of especial interest because it is associated with multipotency, a characteristic that wanes in MSCs as they are culture expanded. Consequently, surface expression of CD271 and CD34 was detected in roughly half of the MSCs cocultured with ECs as spheroids in the presence of insulin-like growth factor 1 (IGF-1). Conversely, expression of CD271 and CD34 was detected in a similar proportion of MSCs cultured under these conditions without ECs, and expression of these markers was low or absent when no IGF-1 was added. These findings indicate that specific culture conditions including IGF-1 can endow cultured MSCs with expression of CD271 and CD34, which may enhance the multipotency of these cells when they are used for therapeutic purposes.

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.

Spheroids from adipose-derived stem cells exhibit an miRNA profile of highly undifferentiated cells

Two-dimensional (2D) cell cultures have been extensively used to investigate stem cell biology, but new insights show that the 2D model may not properly represent the potential of the tissue of origin. Conversely, three-dimensional cultures exhibit protein expression patterns and intercellular junctions that are more representative of their in vivo condition. Multiclonal cells that grow in suspension are defined as "spheroids," and we have previously demonstrated that spheroids from adipose-derived stem cells (S-ASCs) displayed enhanced regenerative capability. With the current study, we further characterized S-ASCs to further understand the molecular mechanisms underlying their stemness properties. Recent studies have shown that microRNAs (miRNAs) are involved in many cellular mechanisms, including stemness maintenance and proliferation, and adipose stem cell differentiation. Most studies have been conducted to identify a specific miRNA profile on adherent adipose stem cells, although little is still known about S-ASCs. In this study, we investigate for the first time the miRNA expression pattern in S-ASCs compared to that of ASCs, demonstrating that cell lines cultured in suspension show a typical miRNA expression profile that is closer to the one reported in induced pluripotent stem cells. Moreover, we have analyzed miRNAs that are specifically involved in two distinct moments of each differentiation, namely early and late stages of osteogenic, adipogenic, and chondrogenic lineages during long-term in vitro culture. The data reported in the current study suggest that S-ASCs have superior stemness features than the ASCs and they represent the true upstream stem cell fraction present in adipose tissue, relegating their adherent counterparts.

Treatment of stress urinary incontinence with low-intensity extracorporeal shock wave therapy in a vaginal balloon dilation induced rat model

Background

To investigate the outcomes and mechanisms of low-intensity extracorporeal shock wave therapy (Li-ESWT) on stress urinary incontinence (SUI) in a vaginal balloon dilation (VBD) rat model.

Methods

Thirty Sprague-Dawley rats were randomly grouped into normal controls, VBD only, and VBD with Li-ESWT. Li-ESWT was administered twice per week for 3 weeks. Afterward, all 30 rats were assessed with functional and histological studies. To explore the acute effect of Li-ESWT, another 25 rats, given intraperitoneal 5-ethynyl-2-deoxyuridine (EdU) at birth, were treated with Li-ESWT followed by assessment of vascular endothelial growth factor (VEGF) expression and endogenous progenitor cells distribution at 24 hours or 1 week after the last Li-ESWT therapy. Additionally, rat myoblast L6 cells were used for myotube formation assay in vitro.

Results

Functional analysis with leak-point pressure (LPP) testing showed that rats treated with Li-ESWT following VBD had significantly higher LPP relative to those receiving VBD only (44.8±3.2 versus 27.0±2.9 cmH₂O, P<0.01). Histological examinations showed increased urethral sphincter regeneration in Li-ESWT group. The rats treated with Li-ESWT also had increased vascularity, which was confirmed by immunohistochemistry of rat endothelial cell antigen, while reverse-transcriptase polymerase chain reaction (RT-PCR) showed VEGF expression was significantly enhanced. Additionally, there were significantly increased EdU+ cells in Li-ESWT treated rats at 24 hours. In vitro, Li-ESWT promoted myotube formation from L6 cells.

Conclusions

Li-ESWT ameliorated SUI by promoting angiogenesis, progenitor cell recruitment, and urethral sphincter regeneration in a rat model induced by VBD. Li-ESWT represents a potential novel non-invasive therapy for SUI.

Are Perivascular Adipocyte Progenitors Mural Cells or Adventitial Fibroblasts?

In their reply, Sylvia Evans and colleagues argue that their lineage-labeling approach gives more precise tracing of the lineage contribution of mural cells in vivo than previous versions.

Role of adipose tissue derived stem cells differentiated into insulin producing cells in the treatment of type I diabetes mellitus

Generation of new β cells is an important approach in the treatment of type 1 diabetes mellitus (type 1 DM). Adipose tissue-derived stem cells (ADSCs) might be one of the best sources for cell replacement therapy for diabetes. Therefore, this work aimed to test the possible role of transplanted insulin-producing cells (IPCs) differentiated from ADSCs in treatment of streptozotocin (STZ) induced type I DM in rats. Type 1 DM was induced by single intra peritoneal injection with STZ (50 mg/kg BW). Half of the diabetic rats were left without treatment and the other half were injected with differentiated IPCs directly into the pancreas. ADSCs were harvested, cultured and identified by testing their phenotypes through flow cytometry. They were further subjected to differentiation into IPCs using differentiation medium. mRNA expression of pancreatic transcription factors (pdx1), insulin and glucose transporter-2 genes by real time PCR was done to detect the cellular differentiation and confirmed by stimulated insulin secretion. The pancreatic tissues from all groups were examined 2 months after IPC transplantation and were subjected to histological, Immunohistochemical and morphometric study. The differentiated IPCs showed significant expression of pancreatic β cell markers and insulin secretion in glucose dependent manner. Treatment with IPCs induced apparent regeneration, diffused proliferated islet cells and significant increase in C-peptide immune reaction. We concluded that transplantation of differentiated IPCs improved function and morphology of Islet cells in diabetic rats. Consequently, this therapy option may be a promising therapeutic approach to patient with type 1 DM if proven to be effective and safe.

A Purification Technique for Adipose-Derived Stromal Cell Cultures Leads to a More Regenerative Cell Population

It has been demonstrated that adipose-derived stromal cells (ASCs) are a regenerative cell population with potential uses for bone and cartilage regeneration. However, the biomarker expression and heterogeneity of the population has not been thoroughly characterized. By analyzing biomarker expression, we aimed to understand the composition of ASC populations extracted using a common extraction technique in comparison to ASC populations given an additional purification step. Human adipose tissue samples were collected, and ASCs were extracted from these samples using a common, published extraction technique (primary extraction). These cells were cultured and half were given an additional purification. The primarily-extracted and purified cell populations were analyzed for biomarkers that correspond to specific cell types. The addition of the purification technique reduced the number of cells expressing hematopoietic and endothelial biomarkers and did not cause the yield of mesenchymal stem cell biomarker-expressing cells to decrease. Biomarkers corresponding to erythrocytes and lymphocytes were lost during the primary extraction, and biomarkers corresponding to most granulocytes and progenitor cells were lost during the additional purification. Biomarkers identifying dendritic cells, monocytes/macrophages, neutrophils, vascular endothelial cells, smooth muscle cells, and pericytes were upregulated in purified cell populations while those identifying fibroblasts and adipocytes were downregulated. Pluripotency biomarkers were more highly expressed in purified cell populations. These results demonstrate that the most commonly utilized adipose tissue recovery and ASC extraction technique leads to a heterogeneous cell population in which further purification of this population, as described in this manuscript, isolates a cell subset that has more regenerative potential.

Comparative characterization of CD271+ and CD271- subpopulations of CD34+ human adipose-derived stromal cells

Adipose-derived stromal/stem cells (ASCs) are promising candidates for cell-based therapies. However, the lack of markers able to unequivocally identify these cells, the differential expression of cell surface molecules among stromal progenitors from different tissues and cellular alterations caused by culture are phenomena that need to be comprehensively addressed in order to improve ASC purification and consequently refine our knowledge about their function and therapeutic efficiency. In this study, we investigated the potential of CD271, a marker used for purification of bone marrow-derived mesenchymal stem cells, on enriching ASCs from CD34⁺ stromal cells of human adipose tissue. Putative ASC populations were sorted based on CD271 expression (CD45^- CD31^- CD34⁺ CD271⁺ and CD45^- CD31^- CD34⁺ CD271^- cells) and compared regarding their clonogenic efficiency, proliferation, immunophenotypic profile, and multilineage potential. To shed light on their native identity, we also interrogated the expression of key perivascular cell markers in freshly isolated cells. CD271^- cells displayed twofold higher clonogenic efficiency than CD271⁺ cells. Upon culture, the progeny of both populations displayed similar immunophenotypic profile and in vitro adipogenic and chondrogenic potentials, while CD271⁺ cells produced more calcified extracellular matrix. Interestingly, uncultured freshly isolated CD271⁺ cells displayed higher expression of pericyte-associated markers than CD271^- cells and localized in the inner region of the perivascular wall. Our results demonstrate that cells with in vitro ASC traits can be obtained from both CD271⁺ and CD271^- stromal populations of human adipose tissue. In addition, gene expression profiling and in situ localization analyses indicate that the CD271⁺ population displays a pericytic phenotype.

Isolation and Flow Cytometric Analysis of the Stromal Vascular Fraction Isolated from Mouse Adipose Tissue

Evidence from preclinical research and clinical trials demonstrates the use of the stromal vascular fraction (SVF) as therapy for numerous indications. These results demonstrate that autologous SVF is not only safe and effective but provides robust anti-inflammatory, immunomodulatory, and reparative effects in vivo. The potency of the SVF is attributed to the cellular composition which includes adipose-derived stem cells (ASCs), adipocytes, endothelial cells, and various immune cells. As the name would suggest, these SVF cells are derived from the stromal compartment of adipose, or fat. Once digested, the cells that constitute adipose are released and collected as the SVF. The cellular frequencies within the SVF can then be assessed using a fluorescent antibody-based technique known as flow cytometry. The following chapter provides a standard operating protocol that describes the procedures from harvesting the fat tissue from experimental mice to isolating and characterizing the SVF.

Plasma Rich in Growth Factors Induces Cell Proliferation, Migration, Differentiation, and Cell Survival of Adipose-Derived Stem Cells

Adipose-derived stem cells (ASCs) are a promising therapeutic alternative for tissue repair in various clinical applications. However, restrictive cell survival, differential tissue integration, and undirected cell differentiation after transplantation in a hostile microenvironment are complications that require refinement. Plasma rich in growth factors (PRGF) from platelet-rich plasma favors human and canine ASC survival, proliferation, and delaying human ASC senescence and autophagocytosis in comparison with serum-containing cultures. In addition, canine and human-derived ASCs efficiently differentiate into osteocytes, adipocytes, or chondrocytes in the presence of PRGF. PRGF treatment induces phosphorylation of AKT preventing ASC death induced by lethal concentrations of hydrogen peroxide. Indeed, AKT inhibition abolished the PRGF apoptosis prevention in ASC exposed to 100 μM of hydrogen peroxide. Here, we show that canine ASCs respond to PRGF stimulus similarly to the human cells regarding cell survival and differentiation postulating the use of dogs as a suitable translational model. Overall, PRGF would be employed as a serum substitute for mesenchymal stem cell amplification to improve cell differentiation and as a preconditioning agent to prevent oxidative cell death.

Low-intensity extracorporeal shock wave therapy promotes myogenesis through PERK/ATF4 pathway

AIM

Stress urinary incontinence (SUI) is a significant health problem for women. Treatments employing muscle derived stem cells (MDSCs) may be a promising approach to this prevalent, bothersome condition, but these treatments are invasive and require collection of cells from one site for injection into another. It is also unknown whether or not these cells establish themselves and function as muscle cells in the target tissues. Alternatively, low-intensity extracorporeal shock wave therapy (Li-ESWT) is non-invasive and has shown positive outcomes in the treatment of multiple musculoskeletal disorders, but the biological effects responsible for clinical success are not yet well understood. The aim of this study is to explore the possibility of employing Li-ESWT for activation of MDSCs in situ and to further elucidate the underlying biological effects and mechanisms of action in urethral muscle.

METHODS

Urethral muscle derived stem cells (uMDSCs) were harvest from Zucker Lean (ZUC-LEAN) (ZUC-Leprfa 186) rats and characterized with flow cytometry. Li-ESWT (0.02 mJ/mm² , 3 Hz, 200 pulses) and GSK2656157, an inhibitor of PERK pathway, were applied to L6 rat myoblast cells. To assess for myotube formation, we used immunofluorescence staining and western blot analysis in uMDSCs and L6 cells.

RESULTS

The results indicate that uMDSCs could form myotubes. Myotube formation was significantly increased by the Li-ESWT as was the expression of muscle heavy chain (MHC) and myogenic factor 5 (Myf5) in L6 cells in vitro. Li-ESWT activated protein kinase RNA-like ER kinase (PERK) pathway by increasing the phosphorylation levels of PERK and eukaryotic initiation factor 2a (eIF2α) and by increasing activating transcription factor 4 (ATF4). In addition, GSK2656157, an inhibitor of PERK, effectively inhibited the myotube formation in L6 rat myoblast cells. Furthermore, GSK2656157 also attenuated myotube formation induced by Li-ESWT.

CONCLUSION

In conclusion, this experiment reveals that rat uMDSCs can be isolated successfully and can form myotubes in vitro. PERK/ATF4 pathway was involved in myotube formation, and L6 rat myoblast cells were activated by Li-ESWT to form myotubes. These findings suggest that PERK/ATF4 pathway is activated by Li-ESWT. This study elucidates one of the biochemical pathways responsible for the clinical improvements seen after Li-ESWT. It is possible that this information will help to establish Li-ESWT as an acceptable treatment modality and may help to further refine the use of Li-ESWT in the clinical practice of medicine.

Update on the mechanisms of homing of adipose tissue-derived stem cells

Adipose tissue-derived stem cells (ADSCs), which resemble bone marrow mesenchymal stromal cells (BMSCs), have shown great advantages and promise in the field of regenerative medicine. They can be readily harvested in large numbers with low donor-site morbidity. To date, a great number of preclinical and clinical studies have shown ADSCs' safety and efficacy in regenerative medicine. However, a better understanding of the mechanisms of homing of ADSCs is needed to advance the clinical utility of this therapy. In this review, the reports of the homing of ADSCs were searched using Pubmed and Google Scholar to update our knowledge. ADSCs were proved to interact with endothelial cells by expressing the similar integrins with BMSCs. In addition, ADSCs do not possess the dominant ligand for P-selectin, just like BMSCs. Stromal derived factor-1 (SDF-1)/CXCR4 and CXC ligand-5 (CXCL5)/CXCR2 interactions are the two main axes governing ADSCs extravasation from bone marrow vessels. Some more signaling pathways involved in migration of ADSCs have been investigated, including LPA/LPA1 signaling pathway, MAPK/Erk1/2 signaling pathway, RhoA/Rock signaling pathway and PDGF-BB/PDGFR-β signaling pathway. Status quo of a lack of intensive studies on the details of homing of ADSCs should be improved in the near future before clinical application.

The contribution of bone marrow-derived cells to the human adipocyte pool

White adipose tissue is a remarkably expandable organ with results in the last decade showing that human white adipocytes are continuously turned over during the entire life-span. Data primarily in murine models have demonstrated that adipocytes are derived from precursors present mainly in the perivascular areas of adipose tissue but their precise origin remains unclear. Subsets of cells present in bone marrow display a multipotent differentiation capacity which has prompted the hypothesis that bone marrow-derived cells (BMDCs) may also contribute to the adipocyte pool present in peripheral fat depots. This notion was initially demonstrated in a murine transplantation model, however, subsequent animal studies have been conflicting resulting in a debate of whether BMDCs actually differentiate into adipocytes or just fuse with resident fat cells. This controversy was recently resolved in 2 studies of human subjects undergoing bone marrow transplantation. Using a combination of different assays these data suggest that bone marrow contributes to at least 10% of the adipocyte pool. This proportion is doubled in obesity, suggesting that BMDCs may constitute a reserve pool for adipogenesis, particularly upon weight gain. This review discusses the possible mechanisms and relevance of these findings for human pathophysiology.

Comparison of intraoperative procedures for isolation of clinical grade stromal vascular fraction for regenerative purposes: a systematic review

Intraoperative application of the stromal vascular fraction (SVF) of adipose tissue requires a fast and efficient isolation procedure of adipose tissue. This review was performed to systematically assess and compare procedures currently used for the intraoperative isolation of cellular SVF (cSVF) and tissue SVF (tSVF) that still contain the extracellular matrix. Pubmed, EMBASE and the Cochrane central register of controlled trials databases were searched for studies that compare procedures for intraoperative isolation of SVF (searched 28 September 2016). Outcomes of interest were cell yield, viability of cells, composition of SVF, duration, cost and procedure characteristics. Procedures were subdivided into procedures resulting in a cSVF or tSVF. Thirteen out of 3038 studies, evaluating 18 intraoperative isolation procedures, were considered eligible. In general, cSVF and tSVF intraoperative isolation procedures had similar cell yield, cell viability and SVF composition compared to a nonintraoperative (i.e. culture laboratory-based collagenase protocol) control group within the same studies. The majority of intraoperative isolation procedures are less time consuming than nonintraoperative control groups, however. Intraoperative isolation procedures are less time-consuming than nonintraoperative control groups with similar cell yield, viability of cells and composition of SVF, and therefore more suitable for use in the clinic. Nevertheless, none of the intraoperative isolation procedures could be designated as the preferred procedure to isolate SVF. Copyright © 2017 John Wiley & Sons, Ltd.

Identification and characterization of a rich population of CD34+ mesenchymal stem/stromal cells in human parotid, sublingual and submandibular glands

Mesenchymal stem/stromal cells (MSCs) play crucial roles in maintaining tissue homeostasis during physiological turnovers and injuries. Very little is known about the phenotype, distribution and molecular nature of MSCs in freshly isolated human salivary glands (SGs) as most reports have focused on the analysis of cultured MSCs. Our results demonstrate that the cell adhesion molecule CD34 was widely expressed by the MSCs of human major SGs, namely parotid (PAG), sublingual (SLG) and submandibular (SMG) glands. Further, gene expression analysis of CD34⁺ cells derived from fetal SMGs showed significant upregulation of genes involved in cellular adhesion, proliferation, branching, extracellular matrix remodeling and organ development. Moreover, CD34⁺ SMG cells exhibited elevated expression of genes encoding extracellular matrix, basement membrane proteins, and members of ERK, FGF and PDGF signaling pathways, which play key roles in glandular development, branching and homeostasis. In vitro CD34⁺ cell derived SG-MSCs revealed multilineage differentiation potential. Intraglandular transplantation of cultured MSCs in immunodeficient mice led to their engraftment in the injected and uninjected contralateral and ipsilateral glands. Engrafted cells could be localized to the stroma surrounding acini and ducts. In summary, our data show that CD34⁺ derived SG-MSCs could be a promising cell source for adoptive cell-based SG therapies, and bioengineering of artificial SGs.

Safety of Allogeneic Canine Adipose Tissue-Derived Mesenchymal Stem Cell Intraspinal Transplantation in Dogs with Chronic Spinal Cord Injury

This is a pilot clinical study primarily designed to assess the feasibility and safety of X-ray-guided percutaneous intraspinal injection of allogeneic canine adipose tissue-derived mesenchymal stem cells in dogs with chronic spinal cord injury. Six dogs with chronic paraplegia (≥six months) were intraparenchymally injected with allogeneic cells in the site of lesion. Cells were obtained from subcutaneous adipose tissue of a healthy dog, cultured to passage 3, labeled with ^99mTechnetium, and transplanted into the lesion by percutaneous X-ray-guided injection. Digital X-ray efficiently guided cell injection as ^99mTechnetium-labeled cells remained in the injection site for at least 24 hours after transplantation. No adverse effects or complications (infection, neuropathic pain, or worsening of neurological function) were observed during the 16-week follow-up period after transplantation. Three animals improved locomotion as assessed by the Olby scale. One animal walked without support, but no changes in deep pain perception were observed. We conclude that X-ray-guided percutaneous intraspinal transplantation of allogeneic cells in dogs with chronic spinal cord injury is feasible and safe. The efficacy of the treatment will be assessed in a new study involving a larger number of animals.

Fibroblast Growth Factor 1-Transfected Adipose-Derived Mesenchymal Stem Cells Promote Angiogenic Proliferation

The aim of this study was to investigate, for the first time, the effects of using adipose-derived mesenchymal stem cells (AD-MSCs) transfected with an episomal plasmid encoding fibroblast growth factor 1 (FGF1) (AD-MSCsFGF1), in providing the microenvironment required for angiogenic proliferation. The isolated rat AD-MSCs were positive for mesenchymal (CD29 and CD90) and negative for hematopoietic (CD34 and CD45) surface markers. Adipogenic and osteogenic differentiation of the AD-MSCs also occurred in the proper culture media. The presence of FGF1 in the conditioned medium from the AD-MSCsFGF1 was confirmed by Western blotting. G418 and PCR were used for selection of transfected cells and confirmation of the presence of FGF1 mRNA, respectively. Treatment with the AD-MSCFGF1-conditioned medium significantly increased the NIH-3T3 cell proliferation and human umbilical vein endothelial cell (HUVEC) tube formation compared to conditioned medium from nontransfected AD-MSCs (p < 0.001). In conclusion, the AD-MSCsFGF1 efficiently secreted functional FGF1, which promoted angiogenic proliferation. Using AD-MSCsFGF1 may provide a useful strategy in cell therapy, which can merge the beneficial effects of stem cells with the positive biological effects of FGF1 in various disorders, especially tissue defects, neurodegenerative, cardiovascular and diabetes endocrine pathologies, which remain to be tested in preclinical and clinical studies.

A Review of Cell-Based Strategies for Soft Tissue Reconstruction

Soft tissue reconstruction to restore volume to damaged or deficient tissue beneath the skin remains a challenging endeavor. Current techniques are centered around autologous fat transfer, or the use of synthetic substitutes, however, a great deal of scientific inquiry has been made into both the molecular mechanisms involved in, and limitations of, de novo adipogenesis, that is, the formation of new adipose tissue from precursor cells. To best comprehend these mechanisms, an understanding of defined markers for adipogenic differentiation, and knowledge of both commercially available and primary cell lines that enable in vitro and in vivo studies is necessary. We review the growth factors, proteins, cytokines, drugs, and molecular pathways that have shown promise in enhancing adipogenesis and vasculogenesis, in addition to the multitude of scaffolds that act as delivery vehicles to support these processes. While progress continues on these fronts, equally important is how researchers are optimizing clinically employed strategies such as autologous fat transfer through cell-based intervention, and the potential to augment this approach through isolation of preferentially adipogenic or angiogenic precursor subpopulations, which exists on the horizon. This review will highlight the novel molecular and synthetic modifications currently being studied for inducing adipose tissue regeneration on a cellular level, which will expand our arsenal of techniques for approaching soft tissue reconstruction.

Extracellular matrix and α5β1 integrin signaling control the maintenance of bone formation capacity by human adipose-derived stromal cells

Stromal vascular fraction (SVF) cells of human adipose tissue have the capacity to generate osteogenic grafts with intrinsic vasculogenic properties. However, adipose-derived stromal/stem cells (ASC), even after minimal monolayer expansion, display poor osteogenic capacity in vivo. We investigated whether ASC bone-forming capacity may be maintained by culture within a self-produced extracellular matrix (ECM) that recapitulates the native environment. SVF cells expanded without passaging up to 28 days (Unpass-ASC) deposited a fibronectin-rich extracellular matrix and displayed greater clonogenicity and differentiation potential in vitro compared to ASC expanded only for 6 days (P0-ASC) or for 28 days with regular passaging (Pass-ASC). When implanted subcutaneously, Unpass-ASC produced bone tissue similarly to SVF cells, in contrast to P0- and Pass-ASC, which mainly formed fibrous tissue. Interestingly, clonogenic progenitors from native SVF and Unpass-ASC expressed low levels of the fibronectin receptor α₅ integrin (CD49e), which was instead upregulated in P0- and Pass-ASC. Mechanistically, induced activation of α₅β₁ integrin in Unpass-ASC led to a significant loss of bone formation in vivo. This study shows that ECM and regulation of α₅β₁-integrin signaling preserve ASC progenitor properties, including bone tissue-forming capacity, during in vitro expansion.

In Situ Activation of Penile Progenitor Cells With Low-Intensity Extracorporeal Shockwave Therapy

BACKGROUND

We previously reported that progenitor cells, or stem cells, exist within penile tissue. We hypothesized that acoustic wave stimulation by low-intensity extracorporeal shockwave therapy (Li-ESWT) would activate local stem or progenitor cells within the penis, producing regenerative effects.

AIMS

To study the feasibility of in situ penile progenitor cell activation by Li-ESWT.

METHODS

We performed a cohort analysis of young and middle-age male Sprague-Dawley rats treated with 5-ethynyl-2'-deoxyuridine (EdU) pulse followed by Li-ESWT. In addition, Li-ESWT was applied to cultured Schwann cells and endothelial cells to study the molecular mechanism involved in cell proliferation. Thirty minutes before Li-ESWT, each rat received an intraperitoneal injection of EdU. Li-ESWT was applied to the penis at very low (0.02 mJ/mm² at 3 Hz for 300 pulses) or low (0.057 mJ/mm² at 3 Hz for 500 pulses) energy levels. The endothelial and Schwann cells were treated with very low energy (0.02 mJ/mm² at 3 Hz for 300 pulses) in vitro.

OUTCOMES

At 48 hours or 1 week after Li-ESWT, penile tissues were harvested for histologic study to assess EdU⁺ and Ki-67⁺ cells, and cell proliferation, Ki-67 expression, Erk1/2 phosphorylation, translocation, and angiogenesis were examined in cultured Schwann and endothelial cells after Li-ESWT.

RESULTS

Li-ESWT significantly increased EdU⁺ cells within penile erectile tissues (P < .01) at 48 hours and 1 week. There were more cells activated in young animals than in middle-age animals, and the effect depended on dosage. Most activated cells were localized within subtunical spaces. In vitro studies indicated that Li-ESWT stimulated cell proliferation through increased phosphorylation of Erk1/2.

CLINICAL TRANSLATION

The present results provide a possible explanation for the clinical benefits seen with Li-ESWT.

STRENGTHS AND LIMITATIONS

The main limitation of the present project was the short period of study and the animal model used. Li-ESWT could be less effective in improving erectile function in old animals because of the decreased number and quality of penile stem or progenitor cells associated with aging.

CONCLUSION

Li-ESWT activation of local penile progenitor cells might be one of the mechanisms that contribute to the beneficial effects of shockwave treatment for erectile dysfunction, which represents a non-invasive alternative to exogenous stem cell therapy. Lin G, Reed-Maldonado AB, Wang B, et al. In Situ Activation of Penile Progenitor Cells With Low-Intensity Extracorporeal Shockwave Therapy. J Sex Med 2017;14:493-501.

Stem cell therapy for the treatment of Peyronie's disease

INTRODUCTION

Like other fibrotic diseases, the cause of Peyronie's disease (PD) is still obscure. Since there is now increasing evidence for the role of Mesenchymal Stem Cells (MSCs) as potential treatment to fibrosis, it is crucial to determine their possible efficacy in the treatment of PD. Areas covered: In this review, the authors summarize the emerging data and published studies regarding the use of SCs for the treatment of PD. The authors provide particular focus on the three-first experimental studies for the use of SCs in rat models as well as the sole two studies undertaken in humans. Expert opinion: It seems evident in experimental settings that SCs in general (Adipose Derived SCs in particular) provide a feasible, safe and effective therapy for PD. The potential limits of the rat models used initially have been somewhat overcome with the inception of studies in men. However, further prospective studies are needed in humans to further elucidate the therapeutic potential of stem cell therapy in PD.