Human orbital adipose tissue-derived mesenchymal stem cells possess neuroectodermal differentiation and repair ability. Cell Tissue Res. 2019;378:531-542. [PMID: 31377878 DOI: 10.1007/s00441-019-03072-0]

Unlocking the versatile potential: Adipose-derived mesenchymal stem cells in ocular surface reconstruction and oculoplastics

This review comprehensively explores the versatile potential of mesenchymal stem cells (MSCs) with a specific focus on adipose-derived MSCs. Ophthalmic and oculoplastic surgery, encompassing diverse procedures for ocular and periocular enhancement, demands advanced solutions for tissue restoration, functional and aesthetic refinement, and aging. Investigating immunomodulatory, regenerative, and healing capacities of MSCs, this review underscores the potential use of adipose-derived MSCs as a cost-effective alternative from bench to bedside, addressing common unmet needs in the field of reconstructive and regenerative surgery.

Characterization of Central and Nasal Orbital Adipose Stem Cells and their Neural Differentiation Footprints

BACKGROUND

The unique potential of stem cells to restore vision and regenerate damaged ocular cells has led to the increased attraction of researchers and ophthalmologists to ocular regenerative medicine in recent decades. In addition, advantages such as easy access to ocular tissues, non-invasive follow-up, and ocular immunologic privilege have enhanced the desire to develop ocular regenerative medicine.

OBJECTIVE

This study aimed to characterize central and nasal orbital adipose stem cells (OASCs) and their neural differentiation potential.

METHODS

The central and nasal orbital adipose tissues extracted during an upper blepharoplasty surgery were explant-cultured in Dulbecco's Modified Eagle Medium (DMEM)/F12 supplemented with 10% fetal bovine serum (FBS). Cells from passage 3 were characterized morphologically by osteogenic and adipogenic differentiation potential and by flow cytometry for expression of mesenchymal (CD73, CD90, and CD105) and hematopoietic (CD34 and CD45) markers. The potential of OASCs for the expression of NGF, PI3K, and MAPK and to induce neurogenesis was assessed by real-time PCR.

RESULTS

OASCs were spindle-shaped and positive for adipogenic and osteogenic induction. They were also positive for mesenchymal and negative for hematopoietic markers. They were positive for NGF expression in the absence of any significant alteration in the expression of PI3K and MAPK genes. Nasal OASCs had higher expression of CD90, higher potential for adipogenesis, a higher level of NGF expression under serum-free supplementation, and more potential for neuron-like morphology.

CONCLUSION

We suggested the explant method of culture as an easy and suitable method for the expansion of OASCs. Our findings denote mesenchymal properties of both central and nasal OASCs, while mesenchymal and neural characteristics were expressed stronger in nasal OASCs when compared to central ones. These findings can be added to the literature when cell transplantation is targeted in the treatment of neuro-retinal degenerative disorders.

Mesenchymal stromal cells-derived secretome protects Neuro-2a cells from oxidative stress-induced loss of neurogenesis

Neurodegenerative diseases (ND) are characterized by debilitating medical conditions that principally affect the neuronal cells in the human brain. One of the major reasons that there are no effective drugs for the treatment of ND is because researchers face technical challenges while conducting studies to understand the molecular mechanism behind ND. Although various studies have established in vitro neurodegenerative model systems, we feel that these model systems are not physiologically relevant, as they do not mimic the in vivo situation of chronic insult. Therefore, the primary aim of this study was to establish an in vitro neurodegenerative model system by inducing oxidative stress in such a way that the neuronal cells remain viable, but lose their structural and functional characteristics. Using a murine neuroblastoma cell line, Neuro-2a, we demonstrate that induction of oxidative stress significantly affects various neurite outgrowth parameters and reduces the expression of neuronal and autophagy markers without causing apoptosis in them. Previously, we have discussed the possible therapeutic applications of mesenchymal stromal cells (MSCs) and their secretome in the treatment of ND. Here, using two distinct approaches, we show that when Neuro-2a cells subjected to oxidative stress are exposed to MSC-derived conditioned medium (secretome), they exhibit a significant improvement in various neuronal parameters and in the expression of neuronal markers. Overall, our findings support the salutary role of MSC-derived secretome in rescuing the oxidative stress-induced loss of neurogenesis using a physiologically relevant in vitro model system. Our data underscore the propensity of the MSC-secretome in reversing ND.

Signaling network regulating osteogenesis in mesenchymal stem cells

Osteogenesis is an important developmental event that results in bone formation. Bone forming cells or osteoblasts develop from mesenchymal stem cells (MSCs) through a highly controlled process regulated by several signaling pathways. The osteogenic lineage commitment of MSCs is controlled by cell-cell interactions, paracrine factors, mechanical signals, hormones, and cytokines present in their niche, which activate a plethora of signaling molecules belonging to bone morphogenetic proteins, Wnt, Hedgehog, and Notch signaling. These signaling pathways individually as well as in coordination with other signaling molecules, regulate the osteogenic lineage commitment of MSCs by activating several osteo-lineage specific transcription factors. Here, we discuss the key signaling pathways that regulate osteogenic differentiation of MSCs and the cross-talk between them during osteogenic differentiation. We also discuss how these signaling pathways can be modified for therapy for bone repair and regeneration.

Review of the potential of mesenchymal stem cells for the treatment of infectious diseases

The therapeutic value of mesenchymal stem cells (MSCs) for the treatment of infectious diseases and the repair of disease-induced tissue damage has been explored extensively. MSCs inhibit inflammation, reduce pathogen load and tissue damage encountered during infectious diseases through the secretion of antimicrobial factors for pathogen clearance and they phagocytose certain bacteria themselves. MSCs dampen tissue damage during infection by downregulating the levels of pro-inflammatory cytokines, and inhibiting the excessive recruitment of neutrophils and proliferation of T cells at the site of injury. MSCs aid in the regeneration of damaged tissue by differentiating into the damaged cell types or by releasing paracrine factors that direct tissue regeneration, differentiation, and wound healing. In this review, we discuss in detail the various mechanisms by which MSCs help combat pathogens, tissue damage associated with infectious diseases, and challenges in utilizing MSCs for therapy.

Adipose-derived mesenchymal stem cells rescue rat hippocampal cells from aluminum oxide nanoparticle-induced apoptosis via regulation of P53, Aβ, SOX2, OCT4, and CYP2E1

Mesenchymal stem cells (MSCs) possess a preventive capacity against free radical toxicity in various tissues. The present study aimed to demonstrate the reformative and treatment roles of adipose-derived MSCs (AD-MSCs) against severe toxicity in the hippocampal cells of the brain caused by aluminum oxide nanoparticles (Al2O3-NPs). Rats were divided into five experimental groups: an untreated control group, a control group receiving NaCl, a group receiving Al2O3-NPs (6 mg/kg) for 20 days, a group that was allowed to recover (R) for 20 days following treatment with Al2O3-NPs, and a Al2O3-NPs + AD-MSCs group, where each rat was injected with 0.8 × 106 AD-MSCs via the caudal vein. Oral administration of Al2O3-NPs increased the protein levels of P53, cleaved caspase-3, CYP2E1, and beta-amyloid (Aβ); contrarily, AD-MSCs transplantation downregulated the levels of these proteins. In addition, the AD-MSCs-treated hippocampal cells were protected from Al2O3-NPs-induced toxicity, as detected by the expression levels of Sox2 and Oct4 that are essential for the maintenance of self-renewal. It was also found that AD-MSCs injection significantly altered the levels of brain total peroxide and monoamine oxidase (MAO)-A and MAO-B activities. Histologically, our results indicated that AD-MSCs alleviated the severe damage in the hippocampal cells induced by Al2O3-NPs. Moreover, the role of AD-MSCs in reducing hippocampal cell death was reinforced by the regulation of P53, cleaved caspase-3, Aβ, and CYP2E1 proteins, as well as by the regulation of SOX2 and OCT4 levels and MAO-A and MAO-B activities.

Adipose tissue plasticity and the pleiotropic roles of BMP signaling

Adipose tissues, including white, beige, and brown adipose tissue, have evolved to be highly dynamic organs. Adipose tissues undergo profound changes during development and regeneration and readily undergo remodeling to meet the demands of an everchanging metabolic landscape. The dynamics are determined by the high plasticity of adipose tissues, which contain various cell types: adipocytes, immune cells, endothelial cells, nerves, and fibroblasts. There are numerous proteins that participate in regulating the plasticity of adipose tissues. Among these, bone morphogenetic proteins (BMPs) were initially found to regulate the differentiation of adipocytes, and they are being reported to have pleiotropic functions by emerging studies. Here, in the first half of the article, we summarize the plasticity of adipocytes and macrophages, which are two groups of cells targeted by BMP signaling in adipose tissues. We then review how BMPs regulate the differentiation, death, and lipid metabolism of adipocytes. In addition, the potential role of BMPs in regulating adipose tissue macrophages is considered. Finally, the expression of BMPs in adipose tissues and their metabolic relevance are discussed.

Role of Mesenchymal Stem Cells in Counteracting Oxidative Stress-Related Neurodegeneration

Neurodegenerative diseases include a variety of pathologies such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, and so forth, which share many common characteristics such as oxidative stress, glycation, abnormal protein deposition, inflammation, and progressive neuronal loss. The last century has witnessed significant research to identify mechanisms and risk factors contributing to the complex etiopathogenesis of neurodegenerative diseases, such as genetic, vascular/metabolic, and lifestyle-related factors, which often co-occur and interact with each other. Apart from several environmental or genetic factors, in recent years, much evidence hints that impairment in redox homeostasis is a common mechanism in different neurological diseases. However, from a pharmacological perspective, oxidative stress is a difficult target, and antioxidants, the only strategy used so far, have been ineffective or even provoked side effects. In this review, we report an analysis of the recent literature on the role of oxidative stress in Alzheimer’s and Parkinson’s diseases as well as in amyotrophic lateral sclerosis, retinal ganglion cells, and ataxia. Moreover, the contribution of stem cells has been widely explored, looking at their potential in neuronal differentiation and reporting findings on their application in fighting oxidative stress in different neurodegenerative diseases. In particular, the exposure to mesenchymal stem cells or their secretome can be considered as a promising therapeutic strategy to enhance antioxidant capacity and neurotrophin expression while inhibiting pro-inflammatory cytokine secretion, which are common aspects of neurodegenerative pathologies. Further studies are needed to identify a tailored approach for each neurodegenerative disease in order to design more effective stem cell therapeutic strategies to prevent a broad range of neurodegenerative disorders.