Stem cell-mediated angiogenesis in skin tissue engineering and wound healing.

The timely management of skin wounds has been an unmet clinical need for centuries. While there have been several attempts to accelerate wound healing and reduce the cost of hospitalisation and the healthcare burden, there remains a lack of efficient and effective wound healing approaches. In this regard, stem cell-based therapies have garnered an outstanding position for the treatment of both acute and chronic skin wounds. Stem cells of different origins (e.g., embryo-derived stem cells) have been utilised for managing cutaneous lesions; specifically, mesenchymal stem cells (MSCs) isolated from foetal (umbilical cord) and adult (bone marrow) tissues paved the way to more satisfactory outcomes. Since angiogenesis plays a critical role in all four stages of normal wound healing, recent therapeutic approaches have focused on utilising stem cells for inducing neovascularisation. In fact, stem cells can promote angiogenesis via either differentiation into endothelial lineages or secreting pro-angiogenic exosomes. Furthermore, particular conditions (e.g., hypoxic environments) can be applied in order to boost the pro-angiogenic capability of stem cells before transplantation. For tissue engineering and regenerative medicine applications, stem cells can be combined with specific types of pro-angiogenic biocompatible materials (e.g., bioactive glasses) to enhance the neovascularisation process and subsequently accelerate wound healing. As such, this review article summarises such efforts emphasising the bright future that is conceivable when using pro-angiogenic stem cells for treating acute and chronic skin wounds.

Stem cell-based therapies for cardiac diseases: The critical role of angiogenic exosomes.

Finding effective treatments for cardiac diseases is among the hottest subjects in medicine; cell-based therapies have brought great promises for managing a broad range of life-threatening heart complications such as myocardial infarction. After clarifying the critical role of angiogenesis in tissue repair and regeneration, various stem/progenitor cell were utilized to accelerate the healing of injured cardiac tissue. Embryonic, fetal, adult, and induced pluripotent stem cells have shown the appropriate proangiogenic potential for tissue repair strategies. The capability of stem cells for differentiating into endothelial lineages was initially introduced as the primary mechanism involved in improving angiogenesis and accelerated heart tissue repair. However, recent studies have demonstrated the leading role of paracrine factors secreted by stem cells in advancing neo-vessel formation. Genetically modified stem cells are also being applied for promoting angiogenesis regarding their ability to considerably overexpress and secrete angiogenic bioactive molecules. Yet, conducting further research seems necessary to precisely identify molecular mechanisms behind the proangiogenic potential of stem cells, including the signaling pathways and regulatory molecules such as microRNAs. In conclusion, stem cells' pivotal roles in promoting angiogenesis and consequent improved cardiac healing and remodeling processes should not be ignored, especially in the case of stem cell-derived extracellular vesicles.

Quantum Dots: A Review from Concept to Clinic.

Quantum dots (QDs) are semiconductor materials that have gained great interest due to their unique characteristics like optical properties. They are extensively being used in different areas, including solar cells, light-emitting diodes, laser technology, as well as biological and biomedical applications. In this review, comprehensive information about different aspects of QDs is provided, including their types and classifications, synthesis approaches, in vitro and in vivo toxicity, biological applications, and potentials in clinical applications. With a focus on the biological aspects, the respective in vitro and in vivo studies are collected and presented. Various surface modifications on QDs are discussed as directly influencing their properties like toxicity and optical abilities. Given the promising results, these materials are clinically used for targeted molecular therapy and imaging. However, there are a large number of questions that should be addressed before the wide application of QDs in a clinical setting. Regarding the existing barriers to QDs, suggestions are given and discussed to present an appropriate route for the clinical use of these materials.

Biomedical applications of nanoceria: new roles for an old player.

The use of different biomaterials with the ability to accelerate the repair and regeneration processes is of great importance in tissue engineering strategies. On this point, cerium oxide nanoparticles (CNPs or nanoceria) have recently attracted much attention due to their excellent biological properties including anti-oxidant, anti-inflammation and antibacterial activities as well as high angiogenic potential. The results of incorporation of these nano-sized particles into various constructs and scaffolds designed for tissue engineering applications have proven the success of this strategy in terms of improving healing process of different tissues. In this review, we first summarize the physicochemical and biological properties of nanoceria in brief and then present its usability in tissue engineering strategies based on the currently available published reports.

Fibroblast Growth Factor Type 1 (FGF1)-Overexpressed Adipose-Derived Mesenchaymal Stem Cells (AD-MSCFGF1) Induce Neuroprotection and Functional Recovery in a Rat Stroke Model.

Stroke, as the second most common cause of death, imposes a great financial burden on both the individual and society. Mesenchymal stem cells from rodents have demonstrated efficacy in experimental animal models of stroke due to enhanced neurological recovery. Since FGF1 (fibroblast growth factor 1) displays neuroprotective properties, for the first time, we investigated the effect of acute intravenous administration of FGF1 gene transfected adipose-derived mesenchymal stem cell (AD-MSCFGF1) on transient experimental ischemic stroke in rats. Stroke induction was made by transient middle cerebral artery occlusion (tMCAO). 2 × 106 AD-MSCFGF1 was administrated intravenously 30 min after carotid reperfusion. The ability of technetium99m-hexamethyl propylene amine oxime (99mTc-HMPAO)-labeled AD-MSCFGF1 to enter into ischemic brain was evaluated 2 h post injection. 24 h post operation, the neurological recovery (rotarod and Roger's tests), the infarct volume (2, 3, 5-triphenyltetrazolium chloride, TTC assay), apoptosis rate (TUNEL assay), and the expression of FGF1 protein (western blotting) in the ischemic hemisphere were assessed. The 99mTc-HMPAO-labeled AD-MSCFGF1 could enter into the ischemic brain. Ischemic hemisphere activity was significantly higher than that observed in the contralateral hemisphere (p = 0.002). The administration of AD-MSCFGF1 resulted in significant improvement of neurological function tests and increased density of FGF1 protein in the peri-infarct area, while the infarct volume and the apoptotic index were significantly decreased, in comparison to the other treated groups. In conclusion, acute intravenous administration of AD-MSCFGF1 can be a novel and promising candidate approach for the treatment of ischemic stroke.

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.

Effects of Streptozotocin-Induced Diabetes on Proliferation and Differentiation Abilities of Mesenchymal Stem Cells Derived from Subcutaneous and Visceral Adipose Tissues.

Introduction: Accumulated evidence indicates that there are intrinsic differences between adipose tissue-derived stem cells (ASCs) obtained from different body fat depots. Here, we compared the proliferation and multipotency of subcutaneous ASCs (SC-ASCs) and epididymal ASCs (ED-ASCs) before and after induction of diabetes by streptozotocin. Methods: The adipogenic and osteogenic abilities of rat SC-ASCs and ED-ASCs were evaluated using Oil Red O and Alizarin Red staining, respectively. The expression of adipocyte (PPAR-γ, LPL) and osteoblast (ALP, SPP1) specific mRNAs was evaluated by quantitative real-time PCR. MTT test was used for determination of cell proliferation capacity. Results: The proliferation of SC-ASCs was higher than ED-ASCs, both before and after diabetes induction (P<0.05). Diabetes increased the proliferative capability of SC-ASCs (P<0.05) but not ED-ASCs. Before diabetes, both adipogenic and osteogenic differentiation of SC-ASCs were higher than ED-ASCs (P<0.05). After diabetes, both SC-ASCs and ED-ASCs were able to differentiate into adipocyte and osteoblast, but the levels of differentiation were higher in SC-ASCs than in ED-ASCs (P<0.05). Diabetes decreased the expression of PPAR-γ and LPL, but increased the SPP1 and ALP expression in both SC-ASCs and ED-ASCs. Conclusion: Our data suggested that diabetes increases the proliferation of ASCs but decreases their adipogenic differentiation. Also, SC-ASCs have higher proliferation and differentiation abilities than ED-ASCs in normal and diabetic conditions so can be more preferable for cell therapy.