Nanotechnology-based products for cancer immunotherapy.

Currently, nanoscale materials and scaffolds carrying antitumor agents to the tumor target site are practical approaches for cancer treatment. Immunotherapy is a modern approach to cancer treatment in which the body's immune system adjusts to deal with cancer cells. Immuno-engineering is a new branch of regenerative medicine-based therapies that uses engineering principles by using biological tools to stimulate the immune system. Therefore, this branch's final aim is to regulate distribution, release, and simultaneous placement of several immune factors at the tumor site, so then upgrade the current treatment methods and subsequently improve the immune system's handling. In this paper, recent research and prospects of nanotechnology-based cancer immunotherapy have been presented and discussed. Furthermore, different encouraging nanotechnology-based plans for targeting various innate and adaptive immune systems will also be discussed. Due to novel views in nanotechnology strategies, this field can address some biological obstacles, although studies are ongoing.

Comparison of osteogenic differentiation potential of induced pluripotent stem cells and buccal fat pad stem cells on 3D-printed HA/ß-TCP collagen-coated scaffolds.

Production of a 3D bone construct with high-yield differentiated cells using an appropriate cell source provides a reliable strategy for different purposes such as therapeutic screening of the drugs. Although adult stem cells can be a good source, their application is limited due to invasive procedure of their isolation and low yield of differentiation. Patient-specific human-induced pluripotent stem cells (hiPSCs) can be an alternative due to their long-term self-renewal capacity and pluripotency after several passages, resolving the requirement of a large number of progenitor cells. In this study, a new biphasic 3D-printed collagen-coated HA/ß-TCP scaffold was fabricated to provide a 3D environment for the cells. The fabricated scaffolds were characterized by the 3D laser scanning digital microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and mechanical test. Then, the osteogenesis potential of the hiPSC-seeded scaffolds was investigated compared to the buccal fat pad stem cell (BFPSC)-seeded scaffolds through in vitro and in vivo studies. In vitro results demonstrated up-regulated expressions of osteogenesis-related genes of RUNX2, ALP, BMP2, and COL1 compared to the BFPSC-seeded scaffolds. In vivo results on calvarial defects in the rats confirmed a higher bone formation in the hiPSC-seeded scaffolds compared to the BFPSC-seeded groups. The immunofluorescence assay also showed higher expression levels of collagen I and osteocalcin proteins in the hiPSC-seeded scaffolds. It can be concluded that using the hiPSC-seeded scaffolds can lead to a high yield of osteogenesis, and the hiPSCs can be used as a superior stem cell source compared to BFPSCs for bone-like construct bioengineering.

Embryonic Stem Cells in Clinical Trials: Current Overview of Developments and Challenges.

The first isolation of human embryonic stem cells (hESC) reported in the late 90s opened a new window to promising possibilities in the fields of human developmental biology and regenerative medicine. Subsequently, the differentiation of hESC lines into different precursor cells showed their potential in treating different incurable diseases. However, this promising field has consistently had remarkable ethical and experimental limitations. This paper is a review of clinical trial studies dealing with hESC and their advantages, limitations, and other specific concerns. Some of the hESC limitations have been solved, and several clinical trial studies are ongoing so that recent clinical trials have strived to improve the clinical applications of hESC, especially in macular degeneration and neurodegenerative diseases. However, regarding hESC-based therapy, several important issues need more research and discussion. Despite considerable studies to Date, hESC-based therapy is not available for conventional clinical applications, and more studies and data are needed to overcome current clinical and ethical limitations. When all the limitations of Embryonic stem cells (ESC) are wholly resolved, perhaps hESC can become superior to the existing stem cell sources. This overview will be beneficial for understanding the standard and promising applications of cell and tissue-based therapeutic approaches and for developing novel therapeutic applications of hESC.

Comparison of human-induced pluripotent stem cells and mesenchymal stem cell differentiation potential to insulin producing cells in 2D and 3D culture systems in vitro.

Diabetes is one of the most common diseases in the world that is chronic, progressive, and costly, and causes many complications. Common drug therapies are not able to cure it, and pancreas transplantation is not responsive to the high number of patients. The production of the insulin producing cells (IPCs) from the stem cells in the laboratory and their transplantation to the patient's body is one of the most promising new approaches. In this study, the differentiation potential of the induced pluripotent stem cells (iPSCs) and mesenchymal stem cells (MSCs) into IPCs was compared to each other while cultured on poly(lactic-co-glycolic) acid (PLGA)/polyethylene glycol (PEG) nanofibrous scaffold as a 3D substrate and tissue culture polystyrene (TCPS) as a 2D substrate. Although the expression level of the insulin, Glut2 and pdx-1 genes in stem cells cultured on 3D substrate was significantly higher than the stem cells cultured on 2D substrate, the highest expression level of these genes was detected in the iPSCs cultured on PLGA-PEG. Insulin and C-peptide secretions from differentiated cells were also investigated and the results showed that secretions in cultured iPSCs on the PLGA-PEG were significantly higher than cultured iPSCs on the TCPS and cultured MSCs on both PLGA-PEG and TCPS. In addition, insulin protein was also expressed in the cultured iPSCs on the PLGA-PEG significantly higher than cultured MSCs on the PLGA-PEG. It can be concluded that differentiation potential of iPSCs into IPCs is significantly higher than human MSCs at both 2D and 3D culture systems.

Polyvinyl alcohol modified polyvinylidene fluoride-graphene oxide scaffold promotes osteogenic differentiation potential of human induced pluripotent stem cells.

Tissue engineering is fast becoming a key approach in bone medicine studies. Designing the ideally desirable combination of stem cells and scaffolds are at the hurt of efforts for producing implantable bone substitutes. Clinical application of stem cells could be associated with serious limitations, and engineering scaffolds that are able to imitate the important features of extracellular matrix is a major area of challenges within the field. In this study, electrospun scaffolds of polyvinylidene fluoride (PVDF), PVDF-graphene oxide (GO), PVDF-polyvinyl alcohol (PVA) and PVDF-PVA-GO were fabricated to study the osteogenic differentiation potential of human induced pluripotent stem cells (iPSCs) while cultured on fabricated scaffolds. Scanning electron microscopy study, viability assay, relative gene expression analysis, immunocytochemistry, alkaline phosphates activity, and calcium content assays confirmed that the osteogenesis rate of hiPSCs cultured on PVDF-PVA-Go is significantly higher than other scaffolds. Here, we showed that the biocompatible, nontoxic, flexible, piezoelectric, highly porous and interconnected three-dimensional structure of electrospun PVDF-PVA-Go scaffold in combination with hiPSCs (as the stem cells with significant advantageous in comparison to other types) makes them a highly promising scaffold-stem cell system for bone remodeling medicine. There was no evidence for the superiority of PVDF-GO or PVDF-PVA scaffold for osteogenesis, compared to each other; however both of them showed better potentials as to PVDF scaffold.

Poly-phosphate increases SMC differentiation of mesenchymal stem cells on PLGA-polyurethane nanofibrous scaffold.

The use of bioactive scaffolds in tissue engineering has a significant effect on the damaged tissue healing by an increase in speed and quality of the process. Herein, electrospinning was applied to fabricate composite nanofibrous scaffolds by Poly lactic-co-glycolic acid (PLGA) and Polyurethane (PU) with and without poly-phosphate (poly-P). Scaffolds were characterized morphologically by scanning electron microscope (SEM), and their biocompatibility was also investigated by SEM, protein adsorption, cell attachment and survival assays. The applicability of the scaffolds for bladder tissue engineering was also evaluated by culturing mesenchymal stem cells (MSCs) on the scaffolds and their differentiation into smooth muscle cell (SMC) was studied at the gene and protein levels. The results demonstrated that scaffold biocompatibility was increased significantly by loading poly-P. SMC related gene and protein expression level in MSCs cultured on poly-P-loaded scaffold was also increased significantly compared to those cells cultured on empty scaffold. It can be concluded that poly-P hasn't also increased scaffold biocompatibility, but also SMC differentiation potential of MSCs was also increased while cultured on the poly-P containing scaffold compared to the empty scaffold. Taken together, our study showed that PLGA-PU-poly-P alone and in combination with MSCs has a promising potential for support urinary bladder smooth muscle tissue engineering.

Adipose-derived stem cells-conditioned medium improved osteogenic differentiation of induced pluripotent stem cells when grown on polycaprolactone nanofibers.

Considering that the common osteogenic growth factors cannot be transplanted with stem cells to the patients, many studies are underway to find a replacement for these factors. Recently, it has been determined that mesenchymal stem cell (MSC)-derived conditioned medium (CM) contains effective factors in the bone formation process. In the current study, the synergistic effect of adipose-derived MSC's CM, and polycaprolactone (PCL) scaffold was investigated on the osteogenic differentiation potential of human induced pluripotent stem cells (iPSCs). After scaffold fabrication by electrospinning and characterization by scanning electron microscopy, iPSCs proliferation in the presence of CM, PCL, and both was evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide. Then, iPSCs osteogenic differentiation was investigated while cultured on tissue culture plate and PCL under CM compared with the osteogenic medium using alizarin red staining, calcium content, alkaline phosphatase activity and gene and protein expression analysis. Proliferation rate of the iPSCs was increased while cultured under CM and its effect was synergistically enhanced by culture on PCL. Evaluation of the osteogenic markers was showed CM alone could induce osteogenic differentiation into the iPSCs and this potential was significantly increased while combined with PCL nanofibrous scaffold. According to the results, it was demonstrated that CM has an osteogenic induction property almost the same of the common osteogenic medium and it can also be used potentially with stem cells when transplant to the patients. CM can also help by prolonging cell survival at the site of the defect as well as accelerating healing process.

Efficient osteogenic differentiation of the dental pulp stem cells on ß-glycerophosphate loaded polycaprolactone/polyethylene oxide blend nanofibers.

Hard tissue lesion treatment in oral and maxillofacial has been challenging because of tissue complexities. This study aimed to investigate novel biopolymeric construct effects on the osteogenic differentiation potential of the dental pulp stem cells (DPSCs) for introducing a cell copolymer bioimplant. A blended polycaprolactone (PCL)-polyethylene oxide (PEO) was fabricated using electrospinning, simultaneously filled by ß-glycerophosphate (ß-GP). After that biocompatibility and release kinetics of the PCL-PEO+ß-GP was evaluated and compared with PCL-PEO and then the osteogenic differentiation potential of the DPSCs was examined while being cultured on the scaffolds and compared with those cultured on the culture plate. The results demonstrated that scaffolds have not any cytotoxicity and ß-GP can release in a long-term manner. Alkaline phosphatase activity and calcium content were significantly increased in DPSCs while being cultured on the PCL-PEO+ß-GP compared with the other groups. Runt-related transcription factor 2, collagen type-I, osteonectin, and osteocalcin (OSC) genes expression was upregulated in DPSCs cultured on the PCL-PEO+ß-GP and was significantly higher than those cultured on the PCL-PEO. Immunocytochemistry result also confirmed the positive effects of PCL-PEO+ß-GP on the osteogenic differentiation of the DPSCs by presenting a higher OSC protein expression. According to the results, incorporation of the ß-GP in PCL-PEO makes a better construct for osteogenic induction into the stem cells and it could be also considered as a great promising candidate for bone, oral, and maxillofacial tissue engineering applications.

Comparison of osteogenic differentiation potential of induced pluripotent stem cells on 2D and 3D polyvinylidene fluoride scaffolds.

In recent decades, tissue engineering has been the most contributor for introducing 2D and 3D biocompatible osteoinductive scaffolds as bone implants. Polyvinylidene fluoride (PVDF), due to the unique mechanical strength and piezoelectric properties, can be a good choice for making a bone bioimplant. In the present study, PVDF nanofibers and film were fabricated as 3D and 2D scaffolds, and then, osteogenic differentiation potential of the human induced pluripotent stem cells (iPSCs) was investigated when grown on the scaffolds by evaluating the common osteogenic markers in comparison with tissue culture plate. Biocompatibility of the fabricated scaffolds was confirmed qualitatively and quantitatively by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and scanning electron microscopy assays. Human iPSCs cultured on PVDF nanofibers showed a significantly higher alkaline phosphate activity and calcium content compared with the iPSCs cultured on PVDF film. Osteogenic-related genes and proteins were also expressed in the iPSCs seeded on PVDF nanofibers significantly higher than iPSCs seeded on PVDF film, when investigated by real-time reverse transcription polymerase chain reaction and western blot analysis, respectively. According to the results, the PVDF nanofibrous scaffold showed a greater osteoinductive property compared with the PVDF film and due to the material similarity of the scaffolds, it could be concluded that the 3D structure could lead to better bone differentiation. Taken together, the obtained results demonstrated that human iPSC-seeded PVDF nanofibrous scaffold could be considered as a promising candidate for use in bone tissue engineering applications.

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) improved osteogenic differentiation of the human induced pluripotent stem cells while considered as an artificial extracellular matrix.

Cocell polymers can be the best implants for replacing bone defects in patients. The pluripotent stem cells produced from the patient and the nanofibrous polymeric scaffold that can be completely degraded in the body and its produced monomers could be also usable are the best options for this implant. In this study, electrospun poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers were fabricated and characterized and then osteogenic differentiation of the human-induced pluripotent stem cells (iPSCs) was investigated while cultured on PHBV scaffold. MTT results showed that cultured iPSCs on PHBV proliferation were increased compared to those cultured on tissue culture polystyrene (TCPS) as the control. Alkaline phosphatase (ALP) activity and calcium content were also significantly increased in iPSCs cultured on PHBV compared to the cultured on TCPS under osteogenic medium. Gene expression evaluation demonstrated that Runx2, collagen type I, ALP, osteonectin, and osteocalcin were upregulated in iPSCs cultured on PHBV scaffold in comparison with those cultured on TCPS for 2 weeks. Western blot analysis have shown that osteocalcin and osteopontin expression as two major osteogenic markers were increased in iPSCs cultured on PHBV scaffold. According to the results, nanofiber-based PHBV has a promising potential to increase osteogenic differentiation of the stem cells and iPSCs-PHBV as a cell-co-polymer construct demonstrated that has a great efficiency for use as a bone tissue engineered bioimplant.

Promoting osteogenic differentiation of human-induced pluripotent stem cells by releasing Wnt/ß-catenin signaling activator from the nanofibers.

Implants that can enhance the stem cells differentiation in the absence of the chemical osteogenic growth factors will attract the great interest of orthopedic scientists. Inorganic polyphosphate (poly-P), as a ubiquitous biological polymer, is one of the factors that can be an alternative for osteogenic growth factors via activating Wnt/ß-catenin signaling. In this study, poly-P was incorporated at the blend of polycaprolactone (PCL)/poly (l-lactic acid) (PLLA) electrospun nanofibers and then osteogenic differentiation potential of human-induced pluripotent stem cells (iPSCs) was investigated by the important bone markers. 3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide (MTT) and scanning electron microscopy results confirmed the biocompatibility of the fabricated nanofibers, while higher proliferation rate of iPSCs was detected in PCL-PLLA(poly-P) group compared with the PCL-PLLA and tissue culture plate groups. Alkaline phosphatase activity, calcium content, and gene expression results demonstrated that osteogenic differentiation of iPSCs was increased when cultured on PCL-PLLA(poly-P) in comparison with other groups. According to the results, PCL-PLLA(poly-P) could be considered as a promising candidate for use as bone implants.

Improved bladder smooth muscle cell differentiation of the mesenchymal stem cells when grown on electrospun polyacrylonitrile/polyethylene oxide nanofibrous scaffold.

Reconstruction of the bladder wall plays an important role in improving its function in patients with urinary bladder dysfunction. Tissue engineering has been trying to introduce biocompatible nanofibers as scaffolds for bladder wall matrix substitutes. In this study a composite nanofibrous scaffold was fabricated from polyacrylonitrile (PAN) and polyethylene oxide (PEO) blend by electrospinning method and then its morphological and mechanical characteristics was evaluated by scanning electron microscopy (SEM), tensile, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Then smooth muscle cell (SMC) differentiation supportive capacity of PAN-PEO nanofibers was investigated by culturing of human adipose tissue-derived mesenchymal stem cells (AT-MSCs) on this scaffold and then its differentiation potential in different groups was investigated using SMC-related gene and protein markers. SEM and MTT results demonstrated that PAN-PEO supported AT-MSCs attachment, growth and proliferation, especially at early times after cell seeding. The obtained results from real-time reverse transcription polymerase chain reaction revealed that collagen-I-α1, collagen-III-α1, α-smooth muscle actin (α-SMA), calponin1, SM22α, caldesmon1, elastin, and myosin heavy chain (MHC) genes were expressed in AT-MSCs cultured on PAN-PEO significantly higher than those stem cells that cultured on the culture plate as a control. In addition α-SMA and MHC proteins were also expressed in AT-MSCs cultured on PAN-PEO significantly higher than control. According to the results PAN-PEO nanofibrous scaffold showed a positive AT-MSCs-seeded PAN-PEO has a great promising potential to use in bladder tissue engineering applications.

Biological behavior of the curcumin incorporated chitosan/poly(vinyl alcohol) nanofibers for biomedical applications.

Electrospun composite scaffolds show high ability to be used in regenerative medicine and drug delivery, due to the nanofibrous structure and high surface area to volume ratio. In this study, we used nanofibrous scaffolds fabricated by chitosan (CS), poly(vinyl alcohol) (PVA), carbopol, and polycaprolactone using a dual electrospinning technique while curcumin (Cur) incorporated inside of the CS/PVA fibers. Scaffolds were fully characterized via scanning electron microscopy, water contact angle, tensile measurement, hydration, protein adsorption, and wrinkled tests. Furthermore, viability of the buccal fat pad-derived mesenchymal stem cells (BFP-MSCs) was also investigated using MTT assay for up to 14 days while cultured on these scaffolds. Cell cycle assay was also performed to more detailed evaluation of the stem cells growth when grown on scaffolds (with and without Cur) compared with the culture plate. Results demonstrated that Cur loaded nanofibrous scaffold had more suitable capability for water absorption and mechanical properties compared with the scaffold without Cur and it could also support the stem cells viability and proliferation. Cur release profile showed a decreasing effect on BFP-MSCs viability in the initial stage, but it showed a positive effect on stem cell viability in a long-term manner. In general, the results indicated that this nanofibrous scaffold has great potential as a delivery of the Cur and BFP-MSCs simultaneously, and so holds the promising potential for use in various regenerative medicine applications.

Improved chondrogenic response of mesenchymal stem cells to a polyethersulfone/polyaniline blended nanofibrous scaffold.

Owing to the fact that the cartilage tissue is not able to repair itself, the treatment of the joint damages is very difficult by current methods. Induction of tissue repair requires suitable cell and extracellular matrix. Providing these two parts can only be done using tissue engineering. In the present study, polyethersulfone (PES) and polyaniline (PANI) blend was electrospined for nanofibrous scaffold fabrication. Mesenchymal stem cells were isolated from human adipose tissue (AT-MSCs), and after characterization cultured on the PES-PANI scaffold and culture plate. Electron microscopic and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assays were used for biocompatibility evaluation of the scaffold and the chondrogenic differentiation potential of AT-MSCs were investigated by staining of proteoglycans and gene and protein expression evaluation. Alcian blue staining, real-time reverse-transcriptase polymerase chain reaction and Western blot results showed that chondrogenic differentiation potential of AT-MSCs was significantly increased when grown on PES-PANI nanofibers and was compared to the one grown on a culture plate. According to the results, PES-PANI has a promising potential to be used as a biomedical implant in patients with joints lesion, such as arthritis and osteoarthritis.

Bone morphogenetic protein-7 incorporated polycaprolactone scaffold has a great potential to improve survival and proliferation rate of the human embryonic kidney cells.

Renal failures treatment has been faced with several problems during the last decades. Kidney tissue engineering has been created many hopes to improve treatment procedures with scaffold fabrication that can modulate kidney cells/stem cells migration to the lesion site and increase the survival of these cells at that site with imitating the role of the kidney extracellular matrix. In this study, bone morphogenetic protein-7 (BMP7) as a vital factor for kidney development and regeneration was incorporated in the polycaprolactone (PCL) nanofibers and after morphological, mechanical, and biocompatible characterization, proliferation, and survival of the human embryonic kidney cells (HEK) were investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, and gene expression while cultured on scaffolds. Mechanical properties of the PCL nanofibers modulated after combining with BMP7 and hydration degree, protein adsorption and cell adhesion were enhanced in PCL-BMP7 compared to the pure PCL. Proliferation rate and growth increased significantly in HEK cells cultured on PCL-BMP7 when compared with that of PCL and tissue culture plate, whereas these data were also confirmed via significant decrease in apoptotic genes expression level in HEK cell cultured on PCL-BMP7. According to the results, PCL-BMP7 demonstrated positive effects on the survival and proliferation rate of the kidney cells and showed has also a great potential to use as a bioimplant for kidney tissue engineering applications.

A comprehensive overview on utilizing electromagnetic fields in bone regenerative medicine.

Stem cells are one of the most important sources to develope  a new strategy for repairing bone lesions through tissue engineering. Osteogenic differentiation of stem cells can be affected by various factors such as biological, chemical, physiological, and physical ones. The application of ELF-EMFs has been the subject of many research in bone tissue engineering and evidence suggests that this exogenous physical stimulus can promote osteogenic differentiation in several types of  cells. The purpose of this paper is to review the current knowledge on the effects of EMFs on stem cells in bone tissue engineering studies. We recapitulated and analyzed 39 articles that were focused on the application of EMFs for bone tissue engineering purposes. We tabulated scattered information from these articles for easy use and tried to provide an overview of conducted research and identify the knowledge gaps in the field.

Osteogenic differentiation potential of mesenchymal stem cells cultured on nanofibrous scaffold improved in the presence of pulsed electromagnetic field.

Nowadays, tissue engineering by using stem cells in combination with scaffolds and bioactive molecules has made significant contributions to the regeneration of damaged bone tissues. Since the usage of bioactive molecules including, growth factors to induce differentiation is safety limited in clinical applications, and it has also been previously observed that extremely low frequency pulsed electromagnetic fields (PEMF) can be effective in the enhancement of proliferation rate and osteogenic differentiation of stem cells, the aim of this study was investigating the osteoinductive potential of PEMF in combination with Poly(caprolactone) (PCL) nanofibrous scaffold. To achieve this aim, Adipose-derived mesenchymal stem cells (ADSCs) isolated and characterized and then osteogenic differentiation of them was investigated after culturing on the surface of PCL scaffold under treatments of PEMF, PEMF plus osteogenic medium (OM) and OM. Analysis of common osteogenic markers such as Alizarin red staining, ALP activity, calcium content and four important bone-related genes in days of 7, 14, and 21 confirmed that the effects of PEMF on the osteogenic differentiation of ADSCs are very similar to the effects of osteogenic medium. Thus, regarding the immunological concerns about the application of bioactive molecules for tissue engineering, PEMF could be a good alternative for osteogenic medium. Although, results were showed a synergetic effect for simultaneous application of PEMF and PCL scaffold in the osteogenesis process of ADSCs. Taking together, ADSCs-seeded PCL nanofibrous scaffold in combination with PEMF could be a great option for use in bone tissue engineering applications.

Bone tissue engineering: Adult stem cells in combination with electrospun nanofibrous scaffolds.

Since bone tissue lesions caused by several reasons and has global outbreak without any attentions to the modernity level of the countries. In the other hands treatment of patients with this problem faced to the several limitations, in this because the future of the bone lesions treatments is related to the future of the bone tissue engineering. This review tries to cover the most suitable stem cells and materials from either natural or synthetic sources for bone tissue engineering. These understanding points would help researchers to further uncover the application of different adult stem cell sources in electrospinning scaffolds, promotion of nanofibrous composite construct design and adult stem cell type selection to enhance cell function and bone tissue engineering, and link laboratory investigations to clinical applications.

The exosomes released from different cell types and their effects in wound healing.

Despite important advances in regenerative medicine and tissue engineering, still, wound healing remains a challenging clinical problem. Cell therapy has opened a new viewpoint in medicine as well as wound management, although it has some limitations. On the other hand, there are some hopes for the eliminated of cellular therapies limitations by "exosomes." The term "exosome" has been frequently used to describe all vesicles released by different cells into the extracellular environment and can influence tissue responses to injury, infection, immune system, and healing. Exosomes contain cytokines and growth factors, signaling lipids, mRNAs, and regulatory miRNAs that have been found in some body fluids and can be transferred between cells to mediating cell-to-cell communication and interactions. Recently, several studies have demonstrated that exosomes are one of the key secretory products of various cell type especially mesenchymal stem cells (MSCs) to regulate many biological processes such wound healing. Hence, understanding these exosomes effects may help to improve wound management and highlight a new therapeutic model for cell-free therapies with decreased side effects for the wound repair.

Different Porosities of Chitosan Can Influence the Osteogenic Differentiation Potential of Stem Cells.

Scaffolds porosity has an important role in in vitro and in vivo differentiation process of stem cells with given the amount of space available to the cells to proliferate and differentiate. In the present study, chitosan with three porosities including 10%, 15%, and 20% that created by gelatin were used for investigation of the proliferation and osteogenic differentiation potential of adipose-derived stem cells (ADSCs). In order to be more like the scaffold to natural bone tissue, freeze-drying method was used in the scaffold preparation. Scaffold morphology, cell attachment, and toxicity were evaluated using scanning electron microscopy and MTT assay. Then, osteogenic differentiation potential of ADSCs cultured on chitosan with different porosities was evaluated by common osteogenic markers such as Alizarin red staining, ALP activity, calcium content, and osteogenic-related genes expression via real-time RT-PCR. Although all scaffolds supported the proliferation and differentiation of ADSCs, but 10% scaffold demonstrated higher amount of osteogenic markers in comparison with the other porosities and control groups. Taking together, it can be concluded that osteogenic differentiation well done in the scaffolds with lower porosity because density of the cells will increase by forcing resulted from the scaffold, so osteogenic differentiation of the stem cells have an inverse association with scaffold porosity. J. Cell. Biochem. 119: 625-633, 2018. © 2017 Wiley Periodicals, Inc.