Neurotrophic features of human adipose tissue-derived stromal cells: in vitro and in vivo studies

The Role of Mesenchymal Stromal Cells and Their Products in the Treatment of Injured Spinal Cords

Spinal cord injury (SCI) is a destructive condition that results in lasting neurological damage resulting in disruption of the connection between the central nervous system and the rest of the body. Currently, there are several approaches in the treatment of a damaged spinal cord; however, none of the methods allow the patient to return to the original full-featured state of life before the injury. Cell transplantation therapies show great potential in the treatment of damaged spinal cords. The most examined type of cells used in SCI research are mesenchymal stromal cells (MSCs). These cells are at the center of interest of scientists because of their unique properties. MSCs regenerate the injured tissue in two ways: (i) they are able to differentiate into some types of cells and so can replace the cells of injured tissue and (ii) they regenerate tissue through their powerful known paracrine effect. This review presents information about SCI and the treatments usually used, aiming at cell therapy using MSCs and their products, among which active biomolecules and extracellular vesicles predominate.

The use of adipose-derived stem cells in cell assisted lipotransfer as potential regenerative therapy in breast reconstruction

Breast reconstruction for breast cancer patients is performed as a standard of care to improve patients' quality of life, physical and psychosocial well-being. Stem cell therapy holds a promise in regenerative medicine, including in breast reconstruction. This review explores the potential use of adipose-derived stem cells (ADSCs) in cell assisted lipotransfer (CAL) for reconstruction of the breast. The review of literature was done using electronic databases using appropriate keywords, including "adipose-derived stem cell", "stem cell therapy", "adipose-derived stem cell", "cell-assisted lipotransfer", "regenerative therapy", "breast cancer" and "breast reconstruction", with literatures limited to ten years post publication. Adipose-derived stem cells are multipotent cells with angiogenic and immunomodulatory potential. Several studies reveal ADSCs use in CAL results in long-term breast volume retention suggesting improved fat graft survival. Some conflicting outcomes are also discussed, potentially related to numbers of cells enriched and factors affecting the cells' microenvironment. The use of ADSCs in CAL may be beneficial for therapy of breast reconstruction in breast cancer patients after surgical management. Further investigation would be needed to improve the confidence of its clinical use.

Current Concepts of Stem Cell Therapy for Chronic Spinal Cord Injury

Chronic spinal cord injury (SCI) is a catastrophic condition associated with significant neurological deficit and social and financial burdens. It is currently being managed symptomatically with no real therapeutic strategies available. In recent years, a number of innovative regenerative strategies have emerged and have been continuously investigated in clinical trials. In addition, several more are coming down the translational pipeline. Among ongoing and completed trials are those reporting the use of mesenchymal stem cells, neural stem/progenitor cells, induced pluripotent stem cells, olfactory ensheathing cells, and Schwann cells. The advancements in stem cell technology, combined with the powerful neuroimaging modalities, can now accelerate the pathway of promising novel therapeutic strategies from bench to bedside. Various combinations of different molecular therapies have been combined with supportive scaffolds to facilitate favorable cell–material interactions. In this review, we summarized some of the most recent insights into the preclinical and clinical studies using stem cells and other supportive drugs to unlock the microenvironment in chronic SCI to treat patients with this condition. Successful future therapies will require these stem cells and other synergistic approaches to address the persistent barriers to regeneration, including glial scarring, loss of structural framework, and immunorejection.

Modulation of Human Adipose Stem Cells' Neurotrophic Capacity Using a Variety of Growth Factors for Neural Tissue Engineering Applications: Axonal Growth, Transcriptional, and Phosphoproteomic Analyses In Vitro

We report on a potential strategy involving the exogenous neurotrophic factors (NTF) for enhancing the neurotrophic capacity of human adipose stem cells (ASC) in vitro. For this, ASC were stimulated for three days using NTF, i.e., nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), NT4, glial cell-derived neurotrophic factor (GDNF), and ciliary neurotrophic factor (CNTF). The resulting conditioned medium (CM) as well as individual NTF exhibited distinct effects on axonal outgrowth from dorsal root ganglion (DRG) explants. In particular, CM derived from NT3-stimulated ASC (CM-NT3-ASC) promoted robust axonal outgrowth. Subsequent transcriptional analysis of DRG cultures in response to CM-NT3-ASC displayed significant upregulation of STAT-3 and GAP-43. In addition, phosphoproteomic analysis of NT3-stimulated ASC revealed significant changes in the phosphorylation state of different proteins that are involved in cytokine release, growth factors signaling, stem cell maintenance, and differentiation. Furthermore, DRG cultures treated with CM-NT3-ASC exhibited significant changes in the phosphorylation levels of proteins involved in tubulin and actin cytoskeletal pathways, which are crucial for axonal growth and elongation. Thus, the results obtained at the transcriptional, proteomic, and cellular level reveal significant changes in the neurotrophic capacity of ASC following NT3 stimulation and provide new options for improving the axonal growth-promoting potential of ASC in vitro.

Differentiation of Mesenchymal Stem Cells to Neuroglia: in the Context of Cell Signalling

The promise of engineering specific cell types from stem cells and rebuilding damaged or diseased tissues has fascinated stem cell researchers and clinicians over last few decades. Mesenchymal Stem Cells (MSCs) have the potential to differentiate into non-mesodermal cells, particularly neural-lineage, consisting of neurons and glia. These multipotent adult stem cells can be used for implementing clinical trials in neural repair. Ongoing research identifies several molecular mechanisms involved in the speciation of neuroglia, which are tightly regulated and interconnected by various components of cell signalling machinery. Growing MSCs with multiple inducers in culture media will initiate changes on intricately interlinked cell signalling pathways and processes. Net result of these signal flow on cellular architecture is also dependent on the type of ligands and stem cells investigated in vitro. However, our understanding about this dynamic signalling machinery is limited and confounding, especially with spheroid structures, neurospheres and organoids. Therefore, the results for differentiating neurons and glia in vitro have been inconclusive, so far. Added to this complication, we have no convincing evidence about the electrical conductivity and functionality status generated in differentiating neurons and glia. This review has taken a step forward to tailor the information on differentiating neuroglia with the common methodologies, in practice.

Hearing regeneration and regenerative medicine: present and future approaches

More than 5% of the world population lives with a hearing impairment. The main factors responsible for hearing degeneration are ototoxic drugs, aging, continued exposure to excessive noise and infections. The pool of adult stem cells in the inner ear drops dramatically after birth, and therefore an endogenous cellular source for regeneration is absent. Hearing loss can emerge after the degeneration of different cochlear components, so there are multiple targets to be reached, such as hair cells (HCs), spiral ganglion neurons (SGNs), supporting cells (SCs) and ribbon synapses. Important discoveries in the hearing regeneration field have been reported regarding stem cell transplantation, migration and survival; genetic systems for cell fate monitoring; and stem cell differentiation to HCs, SGNs and SCs using adult stem cells, embryonic stem cells and induced pluripotent stem cells. Moreover, some molecular mediators that affect the establishment of functional synapses have been identified. In this review, we will focus on reporting the state of the art in the regenerative medicine field for hearing recovery. Stem cell research has enabled remarkable advances in regeneration, particularly in neuronal cells and synapses. Despite the progress achieved, there are certain issues that need a deeper development to improve the results already obtained, or to develop new approaches aiming for the clinical application.

Directed differentiation of human adipose tissue-derived stem cells to dopaminergic neurons in low-serum and serum-free conditions

Directing the fate of mesenchymal stem cells (MSCs) to dopaminergic neurons has great importance in both biomedical studies and cell therapy of Parkinson's disease. We recently generated dopamine-secreting cells from human adipose tissue-derived stem cells (hADSCs) by exposing the cells to a growth factor cocktail composed of SHH, bFGF, FGF8 and BDNF in low-serum condition. In the current study, we induced the cells by the same dopaminergic inducing cocktail in serum-free B27-supplemented Neurobasal medium. ADSCs differentiated in both conditions expressed several neuronal and dopaminergic markers. However, there were higher gene expression levels under the serum-free condition. Higher levels of TUJ1 and TH proteins were also detected in the cells exposed to the dopaminergic-inducing cocktail under serum-free Neurobasal condition. TH protein was expressed in about 28% and 60% of the cells differentiated in the low-serum and serum-free Neurobasal media, respectively. Moreover, the cells exposed to the dopaminergic-inducing cocktail in the serum-free Neurobasal condition released a more significant amount of dopamine in response to KCl-induced depolarization. Altogether, these findings show a greater efficiency of the serum-free Neurobasal condition for growth factor-directed differentiation of hADSCs to functional dopamine-secreting cells which may be valuable for transplantation therapy of Parkinson's disease in future.

Adipose-derived stem cells: Sources, potency, and implications for regenerative therapies

Adipose-derived stem cells (ASCs) are a subset of mesenchymal stem cells (MSCs) that can be obtained easily from adipose tissues and possess many of the same regenerative properties as other MSCs. ASCs easily adhere to plastic culture flasks, expand in vitro, and have the capacity to differentiate into multiple cell lineages, offering the potential to repair, maintain, or enhance various tissues. Since human adipose tissue is ubiquitous and easily obtained in large quantities using a minimally invasive procedure, the use of autologous ASCs is promising for both regenerative medicine and organs damaged by injury and disease, leading to a rapidly increasing field of research. ASCs are effective for the treatment of severe symptoms such as atrophy, fibrosis, retraction, and ulcers induced by radiation therapy. Moreover, ASCs have been shown to be effective for pathological wound healing such as aberrant scar formation. Additionally, ASCs have been shown to be effective in treating severe refractory acute graft-versus-host disease and hematological and immunological disorders such as idiopathic thrombocytopenic purpura and refractory pure red cell aplasia, indicating that ASCs may have immunomodulatory function. Although many experimental procedures have been proposed, standardized harvesting protocols and processing techniques do not yet exist. Therefore, in this review we focus on the current landscape of ASC isolation, identification, location, and differentiation ability, and summarize the recent progress in ASC applications, the latest preclinical and clinical research, and future approaches for the use of ASCs.

Diabetic neuropathy research: from mouse models to targets for treatment

Diabetic neuropathy is one of the most serious complications of diabetes, and its increase shows no sign of stopping. Furthermore, current clinical treatments do not yet approach the best effectiveness. Thus, the development of better strategies for treating diabetic neuropathy is an urgent matter. In this review, we first discuss the advantages and disadvantages of some major mouse models of diabetic neuropathy and then address the targets for mechanism-based treatment that have been studied. We also introduce our studies on each part. Using stem cells as a source of neurotrophic factors to target extrinsic factors of diabetic neuropathy, we found that they present a promising treatment.

In vitro enhancement and functional characterization of neurite outgrowth by undifferentiated adipose-derived stem cells

Adipose‑derived stem cells (ASCs) can easily be obtained and expanded in vitro for use in autologous cell therapy. Via their production of cytokines and neurotrophic factors, transplanted ASCs provide neuroprotection, neovascularization and induction of axonal sprouting. However, the influencing mechanism of undifferentiated ASCs on nerve regeneration is currently only partially understood. In the present study, undifferentiated ASCs and cutaneous primary afferent dorsal root ganglion (DRG) neurons were co‑cultured in order to investigate their interaction. ASCs were isolated from adult rat fat tissue. The presence of characteristic stem cell markers was determined by flow cytometry in three subsequent passages. Adipogenic, osteogenic, chondrogenic and glial differentiation was performed in order to evaluate their differentiation capacity. A direct co‑culture system with DRG cells was established to determine the effect of undifferentiated pluripotent ASCs on neurite elongation. Neurite outgrowth, length and number was examined in the co‑culture and compared with single‑culture cells and cells stimulated with nerve growth factor (NGF). In ASC cultures, NGF expression was assessed by ELISA. The present results demonstrated that the specific mesenchymal stem cell surface markers CD44, CD73 and CD90 were detected in all three subsequent passages of the isolated ASCs. In accordance, ASC differentiation into adipogenic, osteogenic, chondrogenic and Schwann cell phenotype was conducted successfully. Neurite outgrowth of DRG neurons was enhanced following co‑culture with ASCs, resulting in increased neurite length after 24 h of cultivation. Furthermore, neurite outgrowth of DRG neurons was directed towards the undifferentiated ASC and direct cell‑to‑cell contact was observed. In summary, the results of the present study revealed an interaction between the two cell types with guidance of neurite growth towards the undifferentiated ASC. These findings suggest that the use of undifferentiated ASC optimizing tissue‑engineered constructs may be promising for peripheral nerve repair.

Therapy With Mesenchymal Stem Cells in Parkinson Disease: History and Perspectives

BACKGROUND

Parkinson disease (PD) is a neurodegenerative disorder affecting the basal nuclei, causing motor and cognitive disorders. Bearing in mind that standard treatments are ineffective in delaying the disease progression, alternative treatments capable of eliminating symptoms and reversing the clinical condition have been sought. Possible alternative treatments include cell therapy, especially with the use of mesenchymal stem cells (MSC).

REVIEW SUMMARY

MSC are adult stem cells which have demonstrated remarkable therapeutic power in parkinsonian animals due to their differentiation competence, migratory capacity and the production of bioactive molecules. This review aims to analyze the main studies involving MSC and PD in more than a decade of studies, addressing their different methodologies and common characteristics, as well as suggesting perspectives on the application of MSC in PD.

CONCLUSIONS

The results of MSC therapy in animal models and some clinical trials suggest that such cellular therapy may slow the progression of PD and promote neuroregeneration. However, further research is needed to address the limitations of an eventual clinical application.

Secretome released from hydrogel-embedded adipose mesenchymal stem cells protects against the Parkinson's disease related toxin 6-hydroxydopamine

Neurodegenerative diseases, as Parkinson’s disease (PD), involve irreversible neural cell damage and impairment. In PD, there is a selective degeneration of the dopaminergic neurons leading to motor symptoms. A common finding in PD neurodegeneration is the increase of reactive oxygen species (ROS), leading to oxidative stress. To date there are only interventions to relieve PD symptoms, however progress has been made in the development of therapies that target the immune system or use its components as therapeutic agents; among these, mesenchymal stem cells (MSCs), which are able to express neuroprotective factors as cytokines, chemokines and angiogenic molecules, collectively named secretome, that accumulate in MSC culture medium. However, lasting cell-free administration of secretome in vitro or in vivo is challenging. We used the conditioned media from rat adipose tissue-derived MSCs (RAA-MSCs) to check for neuroprotective activity towards pro-oxidizing agents such as hydrogen peroxide (H₂O₂) or the dopaminergic selective toxin 6-hydroxydopamine (6-OHDA) that is commonly used to model PD neurodegeneration. When neuroblastoma SH-SY5Y cells were pre-conditioned with 100% RAA-MSC media, then treated with H₂O₂ and 6-OHDA, mortality and ROS generation were reduced. We implemented the controlled release of RAA-MSC secretome from injectable biodegradable hydrogels that offer a possible in situ implant with mini-invasive techniques. The hydrogels were composed of type I bovine collagen (COLL) and low-molecular-weight hyaluronic acid (LMWHA) or COLL and polyethylene glycol (PEG). Hydrogels were suitable for RAA-MSC embedding up to 48 h and secretome from these RAA-MSCs was active and counteracted 6-OHDA toxicity, with upregulation of the antioxidant enzyme sirtuin 3 (SIRT3). These results support a biomaterials-based approach for controlled delivery of MSC-produced neuroprotective factors in a PD-relevant experimental context.

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.

Adipose-Derived Stem Cells Enhance Axonal Regeneration through Cross-Facial Nerve Grafting in a Rat Model of Facial Paralysis

BACKGROUND

Cross-face nerve grafting combined with functional muscle transplantation has become the standard in reconstructing an emotionally controlled smile in complete irreversible facial palsy. However, the efficacy of this procedure depends on the ability of regenerating axons to breach two nerve coaptations and reinnervate endplates in denervated muscle. The current study tested the hypothesis that adipose-derived stem cells would enhance axonal regeneration through a cross-facial nerve graft and thereby enhance recovery of the facial nerve function.

METHODS

Twelve rats underwent transection of the right facial nerve, and cross-facial nerve grafting using the sciatic nerve as an interpositional graft, with coaptations to the ipsilateral and contralateral buccal branches, was carried out. Rats were divided equally into two groups: a grafted but nontreated control group and a grafted and adipose-derived stem cell-treated group. Three months after surgery, biometric and electrophysiologic assessments of vibrissae movements were performed. Histologically, the spectra of fiber density, myelin sheath thickness, fiber diameter, and g ratio of the nerve were analyzed. Immunohistochemical staining was performed for the evaluation of acetylcholine in the neuromuscular junctions.

RESULTS

The data from the biometric and electrophysiologic analysis of vibrissae movements, immunohistochemical analysis, and histologic assessment of the nerve showed that adipose-derived stem cells significantly enhanced axonal regeneration through the graft.

CONCLUSION

These observations suggest that adipose-derived stem cells could be a clinically translatable route toward new methods to enhance recovery after cross-facial nerve grafting.

Blockade of Neuroglobin Reduces Protection of Conditioned Medium from Human Mesenchymal Stem Cells in Human Astrocyte Model (T98G) Under a Scratch Assay

Previous studies have indicated that paracrine factors (conditioned medium) increase wound closure and reduce reactive oxygen species in a traumatic brain injury in vitro model. Although the beneficial effects of conditioned medium from human adipose tissue-derived mesenchymal stem cells (hMSCA-CM) have been previously suggested for various neurological diseases, their actions on astrocytic cells are not well understood. In this study, we have explored the effect of hMSCA-CM on human astrocyte model (T98G cells) subjected to scratch assay. Our results indicated that hMSCA-CM improved cell viability, reduced nuclear fragmentation, attenuated the production of reactive oxygen species, and preserved mitochondrial membrane potential and ultrastructural parameters. In addition, hMSCA-CM upregulated neuroglobin in T98G cells and the genetic silencing of this protein prevented the protective action of hMSCA-CM on damaged cells, suggesting that neuroglobin is mediating, at least in part, the protective effect of hMSCA-CM. Overall, this evidence suggests that the use of hMSCA-CM is a promising therapeutic strategy for the protection of astrocytic cells in central nervous system (CNS) pathologies.

A Compendium of Preparation and Application of Stem Cells in Parkinson's Disease: Current Status and Future Prospects

Parkinson's Disease (PD) is a progressively neurodegenerative disorder, implicitly characterized by a stepwise loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and explicitly marked by bradykinesia, rigidity, resting tremor and postural instability. Currently, therapeutic approaches available are mainly palliative strategies, including L-3,4-dihydroxy-phenylalanine (L-DOPA) replacement therapy, DA receptor agonist and deep brain stimulation (DBS) procedures. As the disease proceeds, however, the pharmacotherapeutic efficacy is inevitably worn off, worse still, implicated by side effects of motor response oscillations as well as L-DOPA induced dyskinesia (LID). Therefore, the frustrating status above has propeled the shift to cell replacement therapy (CRT), a promising restorative therapy intending to secure a long-lasting relief of patients' symptoms. By far, stem cell lines of multifarious origins have been established, which can be further categorized into embryonic stem cells (ESCs), neural stem cells (NSCs), induced neural stem cells (iNSCs), mesenchymal stem cells (MSCs), and induced pluripotent stem cells (iPSCs). In this review, we intend to present a compendium of preparation and application of multifarious stem cells, especially in relation to PD research and therapy. In addition, the current status, potential challenges and future prospects for practical CRT in PD patients will be elaborated as well.

Updates in the pathophysiological mechanisms of Parkinson’s disease: Emerging role of bone marrow mesenchymal stem cells

AIM: To explore the approaches exerted by mesenchymal stem cells (MSCs) to improve Parkinson’s disease (PD) pathophysiology.

METHODS: MSCs were harvested from bone marrow of femoral bones of male rats, grown and propagated in culture. Twenty four ovariectomized animals were classified into 3 groups: Group (1) was control, Groups (2) and (3) were subcutaneously administered with rotenone for 14 d after one month of ovariectomy for induction of PD. Then, Group (2) was left untreated, while Group (3) was treated with single intravenous dose of bone marrow derived MSCs (BM-MSCs). SRY gene was assessed by PCR in brain tissue of the female rats. Serum transforming growth factor beta-1 (TGF-β1), monocyte chemoattractant protein-1 (MCP-1) and brain derived neurotrophic factor (BDNF) levels were assayed by ELISA. Brain dopamine DA level was assayed fluorometrically, while brain tyrosine hydroxylase (TH) and nestin gene expression were detected by semi-quantitative real time PCR. Brain survivin expression was determined by immunohistochemical procedure. Histopathological investigation of brain tissues was also done.

RESULTS: BM-MSCs were able to home at the injured brains and elicited significant decrease in serum TGF-β1 (489.7 ± 13.0 vs 691.2 ± 8.0, P < 0.05) and MCP-1 (89.6 ± 2.0 vs 112.1 ± 1.9, P < 0.05) levels associated with significant increase in serum BDNF (3663 ± 17.8 vs 2905 ± 72.9, P < 0.05) and brain DA (874 ± 15.0 vs 599 ± 9.8, P < 0.05) levels as well as brain TH (1.18 ± 0.004 vs 0.54 ± 0.009, P < 0.05) and nestin (1.29 ± 0.005 vs 0.67 ± 0.006, P < 0.05) genes expression levels. In addition to, producing insignificant increase in the number of positive cells for survivin (293.2 ± 15.9 vs 271.5 ± 15.9, P > 0.05) expression. Finally, the brain sections showed intact histological structure of the striatum as a result of treatment with BM-MSCs.

CONCLUSION: The current study sheds light on the therapeutic potential of BM-MSCs against PD pathophysiology via multi-mechanistic actions.

Human adipose-derived mesenchymal stem cells improve motor functions and are neuroprotective in the 6-hydroxydopamine-rat model for Parkinson's disease when cultured in monolayer cultures but suppress hippocampal neurogenesis and hippocampal memory function when cultured in spheroids

Adult human adipose-derived mesenchymal stem cells (MSC) have been reported to induce neuroprotective effects in models for Parkinson's disease (PD). However, these effects strongly depend on the most optimal application of the transplant. In the present study we compared monolayer-cultured (aMSC) and spheroid (sMSC) MSC following transplantation into the substantia nigra (SN) of 6-OHDA lesioned rats regarding effects on the local microenvironment, degeneration of dopaminergic neurons, neurogenesis in the hippocampal DG as well as motor and memory function in the 6-OHDA-rat model for PD. aMSC transplantation significantly increased tyrosine hydroxylase (TH) and brain-derived neurotrophic factor (BDNF) levels in the SN, increased the levels of the glial fibrillary acidic protein (GFAP) and improved motor functions compared to untreated and sMSC treated animals. In contrast, sMSC grafting induced an increased local microgliosis, decreased TH levels in the SN and reduced numbers of newly generated cells in the dentate gyrus (DG) without yet affecting hippocampal learning and memory function. We conclude that the neuroprotective potential of adipose-derived MSC in the rat model of PD crucially depends on the applied cellular phenotype.

Dedifferentiated fat cells: A cell source for regenerative medicine

The identification of an ideal cell source for tissue regeneration remains a challenge in the stem cell field. The ability of progeny cells to differentiate into other cell types is important for the processes of tissue reconstruction and tissue engineering and has clinical, biochemical or molecular implications. The adaptation of stem cells from adipose tissue for use in regenerative medicine has created a new role for adipocytes. Mature adipocytes can easily be isolated from adipose cell suspensions and allowed to dedifferentiate into lipid-free multipotent cells, referred to as dedifferentiated fat (DFAT) cells. Compared to other adult stem cells, the DFAT cells have unique advantages in their abundance, ease of isolation and homogeneity. Under proper condition in vitro and in vivo, the DFAT cells have exhibited adipogenic, osteogenic, chondrogenic, cardiomyogenc, angiogenic, myogenic, and neurogenic potentials. In this review, we first discuss the phenomena of dedifferentiation and transdifferentiation of cells, and then dedifferentiation of adipocytes in particular. Understanding the dedifferentiation process itself may contribute to our knowledge of normal growth processes, as well as mechanisms of disease. Second, we highlight new developments in DFAT cell culture and summarize the current understanding of DFAT cell properties. The unique features of DFAT cells are promising for clinical applications such as tissue regeneration.

Changes of neural markers expression during late neurogenic differentiation of human adipose-derived stem cells

BACKGROUND

Different studies have been done to obtain sufficient number of neural cells for treatment of neurodegenerative diseases, spinal cord, and traumatic brain injury because neural stem cells are limited in central nerves system. Recently, several studies have shown that adipose-derived stem cells (ADSCs) are the appropriate source of multipotent stem cells. Furthermore, these cells are found in large quantities. The aim of this study was an assessment of proliferation and potential of neurogenic differentiation of ADSCs with passing time.

MATERIALS AND METHODS

Neurosphere formation was used for neural induction in isolated human ADSCs (hADSCs). The rate of proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and potential of neural differentiation of induced hADSCs was evaluated by immunocytochemical and real-time reverse transcription polymerase chain reaction analysis after 10 and 14 days post-induction.

RESULTS

The rate of proliferation of induced hADSCs increased after 14 days while the expression of nestin, glial fibrillary acidic protein, and microtubule-associated protein 2 was decreased with passing time during neurogenic differentiation.

CONCLUSION

These findings showed that the proliferation of induced cells increased with passing time, but in early neurogenic differentiation of hADSCs, neural expression was higher than late of differentiation. Thus, using of induced cells in early differentiation may be suggested for in vivo application.

Time-Dependent Effect of Encapsulating Alginate Hydrogel on Neurogenic Potential

OBJECTIVE

Due to the restricted potential of neural stem cells for regeneration of central nervous system (CNS) after injury, providing an alternative source for neural stem cells is essential. Adipose derived stem cells (ADSCs) are multipotent cells with properties suitable for tissue engineering. In addition, alginate hydrogel is a biocompatible polysaccharide polymer that has been used to encapsulate many types of cells. The aim of this study was to assess the proliferation rate and level of expression of neural markers; NESTIN, glial fibrillary acidic protein (GFAP) and microtubule-associated protein 2 (MAP2) in encapsulated human ADSCs (hADSCs) 10 and14 days after neural induction.

MATERIALS AND METHODS

In this experimental study, ADSCs isolated from human were cultured in neural induction media and seeded into alginate hydrogel. The rate of proliferation and differentiation of encapsulated cells were evaluated by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) assay, immunocytoflourescent and realtime reverse transcriptase polymerase chain reaction (RT-PCR) analyzes 10 and 14 days after induction.

RESULTS

The rate of proliferation of encapsulated cells was not significantly changed with time passage. The expression of NESTIN and GFAP significantly decreased on day 14 relative to day 10 (P<0.001) but MAP2 expression was increased.

CONCLUSION

Alginate hydrogel can promote the neural differentiation of encapsulated hADSCs with time passage.

The expression of neurogenic markers after neuronal induction of chorion-derived mesenchymal stromal cells

OBJECTIVES

Chorion is a tissue of early embryologic period that is discarded after delivery. It might be the potential source of mesenchymal stromal cells (MSCs) that can be used for research and eventually for therapeutic studies. At present, the biological properties and the differentiation capacity of chorion-derived MSCs are still poorly characterised. The objective of this study is to characterise and explore the differentiating potential of chorion-derived MSCs towards the neuronal lineages.

METHODS

Chorionic membrane was digested with enzyme and cultured in Dulbecco's Modified Eagle's medium supplemented with 10% fetal bovine serum. The expression of MSC markers was examined using flow cytometry. The adipogenic, osteogenic and neurogenic differentiation were examined by culturing in appropriate induction media. The expression of neuronal markers was determined by immunofluorescence and quantitative real time-PCR.

RESULTS

Chorion-derived MSCs were easily expanded up to 20 passages. They were positive for MSC markers (CD73, CD90 and CD105), and negative for haematopoietic markers (CD34 and CD45). Chorion-derived MSCs could differentiate into several mesodermal-lineages including adipocytes and osteoblasts. Moreover, chorion-derived MSCs could differentiate into neuronal-like cells as characterised by cell morphology and the presence of neural markers including MAP-2, glial fibrillary acidic protein (GFAP) and beta-tubulin III.

DISCUSSION

Chorion-derived MSCs can be readily obtained and expanded in culture. These cells also have transdifferentiation capacity as evidenced by their neuronal differentiation potential. Therefore, chorion can be used as an alternative source of MSCs for stem cell therapy in nervous system disorders.

Adipose-derived stem cells for nerve repair: hype or reality?

Peripheral nerve injury is a relatively commonly occurring trauma which seriously compromises the quality of life for many individuals. There is a major need to devise new treatment strategies, and one possible approach is to develop cellular therapies to bioengineer new nerve tissue and/or modulate the endogenous regenerative mechanisms within the peripheral nervous system. In this short review we describe how stem cells isolated from adipose tissue could be a suitable element of this approach. We describe the possible mechanisms through which the stem cells might exert a positive influence on peripheral nerve regeneration. These include their ability to differentiate into cells resembling Schwann cells and their secretion of a plethora of neurotrophic growth factors. We also review the literature describing the effects of these cells when tested using in vivo peripheral nerve injury models.

Implications for human adipose-derived stem cells in plastic surgery

Adipose-derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs) that possess many of the same regenerative properties as other MSCs. However, the ubiquitous presence of ADSCs and their ease of access in human tissue have led to a burgeoning field of research. The plastic surgeon is uniquely positioned to harness this technology because of the relative frequency in which they perform procedures such as liposuction and autologous fat grafting. This review examines the current landscape of ADSC isolation and identification, summarizes the current applications of ADSCs in the field of plastic surgery, discusses the risks associated with their use, current barriers to universal clinical translatability, and surveys the latest research which may help to overcome these obstacles.

Grafting and early expression of growth factors from adipose-derived stem cells transplanted into the cochlea, in a Guinea pig model of acoustic trauma

Noise exposure causes damage of multiple cochlear cell types producing permanent hearing loss with important social consequences. In mammals, no regeneration of either damaged hair cells or auditory neurons has been observed and no successful treatment is available to achieve a functional recovery. Loads of evidence indicate adipose-derived stem cells (ASCs) as promising tools in diversified regenerative medicine applications, due to the high degree of plasticity and trophic features. This study was aimed at identifying the path of in vivo cell migration and expression of trophic growth factors, upon ASCs transplantation into the cochlea, following noise-induced injury. ASCs were isolated in primary culture from the adipose tissue of a guinea pig, transduced using a viral vector to express the green fluorescent protein, and implanted into the scala tympani of deafened animals. Auditory function was assessed 3 and 7 days after surgery. The expression of trophic growth factors was comparatively analyzed using real-time PCR in control and noise-injured cochlear tissues. Immunofluorescence was used to assess the in vivo localization and expression of trophic growth factors in ASCs and cochleae, 3 and 7 days following homologous implantation. ASC implantation did not modify auditory function. ASCs migrated from the perilymphatic to the endolymphatic compartment, during the analyzed time course. Upon noise exposure, the expression of chemokine ligands and receptors related to the PDGF, VEGF, and TGFbeta pathways, increased in the cochlear tissues, possibly guiding in vivo cell migration. Immunofluorescence confirmed the increased expression, which appeared to be further strengthened by ASCs’ implantation. These results indicated that ASCs are able to migrate at the site of tissue damage and express trophic factors, upon intracochlear implantation, providing an original proof of principle, which could pave the way for further developments of ASC-based treatments of deafness.

Spinal fusion in the next generation: gene and cell therapy approaches

Bone fusion represents a challenge in the orthopedics practice, being especially indicated for spine disorders. Spinal fusion can be defined as the bony union between two vertebral bodies obtained through the surgical introduction of an osteoconductive, osteoinductive, and osteogenic compound. Autogenous bone graft provides all these three qualities and is considered the gold standard. However, a high morbidity is associated with the harvest procedure. Intensive research efforts have been spent during the last decades to develop new approaches and technologies for successful spine fusion. In recent years, cell and gene therapies have attracted great interest from the scientific community. The improved knowledge of both mesenchymal stem cell biology and osteogenic molecules allowed their use in regenerative medicine, representing attractive approaches to achieve bone regeneration also in spinal surgery applications. In this review we aim to describe the developing gene- and cell-based bone regenerative approaches as promising future trends in spine fusion.

Stimulating the neurotrophic and angiogenic properties of human adipose-derived stem cells enhances nerve repair

In future, adipose-derived stem cells (ASC) might be used to treat neurological disorders. In this study, the neurotrophic and angiogenic properties of human ASC were evaluated, and their effects in a peripheral nerve injury model were determined. In vitro growth factor stimulation of the cells resulted in increased secretion of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), vascular endothelial growth factor-A (VEGF-A), and angiopoietin-1 proteins. Conditioned medium from stimulated cells increased neurite outgrowth of dorsal root ganglia (DRG) neurons. Similarly, stimulated cells showed an enhanced ability to induce capillary-like tube formation in an in vitro angiogenesis assay. ASC were seeded into a fibrin conduit that was used to bridge a 10 mm rat nerve gap. After 2 weeks, the animals treated with control or stimulated ASC showed an enhanced axon regeneration distance. Stimulated cells evoked more total axon growth. Analysis of regeneration and apoptosis-related gene expression showed that both ASC and stimulated ASC enhanced GAP-43 and activating transcription factor 3 (ATF-3) expression in the spinal cord and reduced c-jun expression in the DRG. Caspase-3 expression in the DRG was reduced by stimulated ASC. Both ASC and stimulated ASC also increased the vascularity of the fibrin nerve conduits. Thus, ASC produce functional neurotrophic and angiogenic factors, creating a more desirable microenvironment for nerve regeneration.

Stem cells in plastic surgery: a review of current clinical and translational applications

BACKGROUND

Stem cells are a unique cell population characterized by self-renewal and cellular differentiation capabilities. These characteristics, among other traits, make them an attractive option for regenerative treatments of tissues defects and for aesthetic procedures in plastic surgery. As research regarding the isolation, culture and behavior of stem cells has progressed, stem cells, particularly adult stem cells, have shown promising results in both translational and clinical applications.

METHODS

The purpose of this review is to evaluate the applications of stem cells in the plastic surgery literature, with particular focus on the advances and limitations of current stem cell therapies. Different key areas amenable to stem cell therapy are addressed in the literature review; these include regeneration of soft tissue, bone, cartilage, and peripheral nerves, as well as wound healing and skin aging.

RESULTS

The reviewed studies demonstrate promising results, with favorable outcomes and minimal complications in the cited cases. In particular, adipose tissue derived stem cell (ADSC) transplants appear to provide effective treatment options for bony and soft tissue defects, and non-healing wounds. ADSCs have also been shown to be useful in aesthetic surgery.

CONCLUSIONS

Further studies involving both the basic and clinical science aspects of stem cell therapies are warranted. In particular, the mechanism of action of stem cells, their interactions with the surrounding microenvironment and their long-term fate require further elucidation. Larger randomized trials are also necessary to demonstrate the continued safety of transplanted stem cells as well as the efficacy of cellular therapies in comparison to the current standards of care.

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.

Neuromodulatory nerve regeneration: adipose tissue-derived stem cells and neurotrophic mediation in peripheral nerve regeneration

Peripheral nerve injury requiring nerve gap reconstruction remains a major problem. In the quest to find an alternative to autogenous nerve graft procedures, attempts have been made to differentiate mesenchymal stem cells into neuronal lineages in vitro and utilize these cellular constructs for nerve regeneration. Unfortunately, this has produced mixed results, with no definitive procedure matching or surpassing traditional nerve grafting procedures. This review presents a different approach to nerve regeneration. The literature was reviewed to evaluate current methods of using adipose-derived stem cells (ADSCs) for peripheral nerve regeneration in in vivo models of animal peripheral nerve injury. The authors present cited evidence for directing nerve regeneration through paracrine effects of ADSCs rather than through in vitro nerve regeneration. The paracrine effects rely mainly, but not solely, on the elaboration of nerve growth factors and neurotrophic mediators that influence surrounding host cells to orchestrate in vivo nerve regeneration. Although this paradigm has been indirectly referred to in a host of publications, few major efforts for this type of neuromodulatory nerve regeneration have been forthcoming. The ADSCs are initially "primed" in vitro using specialized controlled medium (not for neuronal differentiation but for sustainability) and then incorporated into a hydrogel base matrix designed for this purpose. This core matrix is then introduced into a natural collagen-based nerve conduit. The prototype design concepts, evidence for paracrine influences, and regulatory hurdles that are avoided using this approach are discussed.

Update on small intestinal stem cells

Among somatic stem cells, those residing in the intestine represent a fascinating and poorly explored research field. Particularly, somatic stem cells reside in the small intestine at the level of the crypt base, in a constant balance between self-renewal and differentiation. Aim of the present review is to delve into the mechanisms that regulate the delicate equilibrium through which intestinal stem cells orchestrate intestinal architecture. To this aim, special focus will be addressed to identify the integrating signals from the surrounding niche, supporting a model whereby distinct cell populations facilitate homeostatic vs injury-induced regeneration.

Harvest site influences the growth properties of adipose derived stem cells

The therapeutic potential of adult stem cells may become a relevant option in clinical care in the future. In hand and plastic surgery, cell therapy might be used to enhance nerve regeneration and help surgeons and clinicians to repair debilitating nerve injuries. Adipose-derived stem cells (ASCs) are found in abundant quantities and can be harvested with a low morbidity. In order to define the optimal fat harvest location and detect any potential differences in ASC proliferation properties, we compared biopsies from different anatomical sites (inguinal, flank, pericardiac, omentum, neck) in Sprague-Dawley rats. ASCs were expanded from each biopsy and a proliferation assay using different mitogenic factors, basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) was performed. Our results show that when compared with the pericardiac region, cells isolated from the inguinal, flank, omental and neck regions grow significantly better in growth medium alone. bFGF significantly enhanced the growth rate of ASCs isolated from all regions except the omentum. PDGF had minimal effect on ASC proliferation rate but increases the growth of ASCs from the neck region. Analysis of all the data suggests that ASCs from the neck region may be the ideal stem cell sources for tissue engineering approaches for the regeneration of nervous tissue.

Epigenetic regulation of nestin expression during neurogenic differentiation of adipose tissue stem cells

Adipose-tissue-derived stem cells (ASCs) have received considerable attention due to their easy access, expansion potential, and differentiation capacity. ASCs are believed to have the potential to differentiate into neurons. However, the mechanisms by which this may occur remain largely unknown. Here, we show that culturing ASCs under active proliferation conditions greatly improves their propensity to differentiate toward osteogenic, adipogenic, and neurogenic lineages. Neurogenic-induced ASCs express early neurogenic genes as well as markers of mature neurons, including voltage-gated ion channels. Nestin, highly expressed in neural progenitors, is upregulated by mitogenic stimulation of ASCs, and as in neural progenitors, then repressed during neurogenic differentiation. Nestin gene (NES) expression under these conditions appears to be regulated by epigenetic mechanisms. The neural-specific, but not muscle-specific, enhancer regions of NES are DNA demethylated by mitogenic stimulation, and remethylated upon neurogenic differentiation. We observe dynamic changes in histone H3K4, H3K9, and H3K27 methylation on the NES locus before and during neurogenic differentiation that are consistent with epigenetic processes involved in the regulation of NES expression. We suggest that ASCs are epigenetically prepatterned to differentiate toward a neural lineage and that this prepatterning is enhanced by demethylation of critical NES enhancer elements upon mitogenic stimulation preceding neurogenic differentiation. Our findings provide molecular evidence that the differentiation repertoire of ASCs may extend beyond mesodermal lineages.