Evaluation of colonic anastomosis healing using hybrid nanosheets containing molybdenum disulfide (MOS2) scaffold of human placental amniotic membrane and polycaprolactone (PCL) in rat animal model.

Anastomosis is a standard technique following different conditions such as obstruction, tumor, and trauma. Obstruction, adhesion, or anastomosis leakage can be some of its complications. To improve healing and prevent postoperative complications, we design a hybrid scaffold containing acellular human amniotic membranes and polycaprolactone-molybdenum disulfide nanosheets for colon anastomosis. The animal model of colocolonic anastomosis was performed on two groups of rats: control and scaffold. The hybrid scaffold was warped around the anastomosis site in the scaffold group. Samples from the anastomosis site were resected on the third and seventh postoperative days for histopathological and molecular assessments. Histopathologic score and burst pressure had shown significant improvement in the scaffold group. No mortality and anastomosis leakage was reported in the scaffold group. In addition, inflammatory markers were significantly decreased, while anti-inflammatory cytokines were increased in the scaffold group. The result indicates that our hybrid scaffold is a proper choice for colorectal anastomosis repair by declining postoperative complications and accelerating healing.

Scaphoid Bone Nonunions: Clinical and Functional Outcomes of Collagen/PGA Scaffolds and Cell-Based Therapy.

In this study, the procedure for treating the nonunion complication of scaphoid fractures using collagen/poly glycolic acid (CPGA) scaffolds with bone marrow mesenchymal stem cell (BM-MSC) therapy was adopted and compared with the commonly employed autologous bone tissue graft. With conducting a two-armed clinical trial, 10 patients with scaphoid nonunions were enrolled in this investigation. Patients were randomly assigned to two groups treated with (1) CPGA + cell therapy and (2) autologous iliac crest bone graft standard therapy. Treatment outcomes were evaluated three months after surgery, measuring the grip and pinch strengths and wrist range of motion, with two questionnaires: Patient-Rated Wrist Evaluation (PRWE) and Quick form of Disabilities of the Arm, Shoulder, and Hand (QDASH). We have also assessed the union rate using clinical and radiologic healing criteria one and three months post-operatively. Restorative effects of CPGA + cell therapy were similar to those of the autologous bone graft standard therapy, except for the grip strength (P = 0.048) and QDASH score (P = 0.044) changes, which were higher in the CPGA + cell therapy group. Three months following the surgery, radiographic images and computed tomography (CT) scans also demonstrated that the scaphoid union rate in the test group was comparable to that of scaphoids treated with the standard autograft method. Our findings demonstrate that the CPGA + cell therapy is a potential alternative for bone grafting in the treatment of bone nonunions.

Safety and efficacy of injection of human placenta mesenchymal stem cells derived exosomes for treatment of complex perianal fistula in non-Crohn's cases: Clinical trial phase I.

BACKGROUND AND AIM: A perianal fistula is an abnormal tract that connects anal canal to skin. Current medical and surgical interventions have a high failure rate particularly in complex and refractory cases. MSC-derived exosomes have demonstrated immunomodulatory effects without the conventional complications; hence, in this study, we evaluated the safety of their application for complex perianal fistula. METHODS: Placenta-derived MSCs were cultured, and exosomes were isolated using ultracentrifugation. Exosome injections were administered in the operating room to 11 patients with complex perianal fistula (presence of fistulas for at least 1 year alongside medical and surgical treatment). The patients were followed for 6 months, and the patients were evaluated using physical examination, face-to-face interviews, and magnetic resonance imaging (MRI). RESULTS: Among 11 patients only one did not show any improvement upon physical examination. Five patients showed complete tract resolve. While the discharge was stopped in eight patients, two patients showed only reduction. None of the patients showed any acute or latent allergic reaction or injection related complications. CONCLUSION: Administration of exosomes isolated from MSCs demonstrates safety and a satisfactory therapeutic effect in treatment complex perianal fistulae; therefore, it can be a candidate for future studies and might play a significant role in treatment.

Advanced micro-/nanotechnologies for exosome encapsulation and targeting in regenerative medicine.

Exosomes, a subset of vesicles generated from cell membranes, are crucial for cellular communication. Exosomes' innate qualities have been used in recent studies to create nanocarriers for various purposes, including medication delivery and immunotherapy. As a result, a wide range of approaches has been designed to utilize their non-immunogenic nature, drug-loading capacity, or targeting ability. In this study, we aimed to review the novel methods and approaches in exosome engineering for encapsulation and targeting in regenerative medicine. We have assessed and evaluated each method's efficacy, advantages, and disadvantages and discussed the results of related studies. Even though the therapeutic role of non-allogenic exosomes has been demonstrated in several studies, their application has certain limitations as these particles are neither fully specific to target tissue nor tissue retainable. Hence, there is a strong demand for developing more efficient encapsulation methods along with more accurate and precise targeting methods, such as 3D printing and magnetic nanoparticle loading in exosomes, respectively.

Design and fabrication of polyvinylidene fluoride-graphene oxide/gelatine nanofibrous scaffold for cardiac tissue engineering.

Polyvinylidene fluoride (PVDF) electrospun scaffolds have recently been developed for cardiac tissue engineering applications thanks to their piezoelectricity. However, PVDFs' hydrophobic nature requires modifications by incorporating natural polymers. In this study, we focussed on the hybrid electrospinning of PVDF and gelatine and the further introduction of graphene oxide nanoparticles to investigate either hydrophilicity or piezoelectricity enhancement and its impact on mouse embryonic cardiomyocytes. The results revealed a nanofibre diameter of 379 ± 73 nm for the PVDF/gelatine/graphene oxide (PVDF-GO-CG) platform, providing excellent tensile strength. Additionally, hydrophilicity was improved by gelatine and GO incorporation compared with pure PVDF. Cellular studies also showed an elongated morphology of cardiomyocytes, similar to the myocardial tissue, as well as high viability and non-toxicity in the PVDF-GO-CG scaffold according to the average survival rate. Furthermore, the expression of connexin 43 and troponin T genes underwent an increment of 41 and 35% in the PVDF-GO-CG compared with the PVDF-CG sample. This study proves the applicability of the PVDF-GO-CG scaffold as an alternative substrate for developing engineered cardiac tissues by providing an environment to re-establish their synchronised communications.

Evaluating the safety and efficacy of mesenchymal stem cell-derived exosomes for treatment of refractory perianal fistula in IBD patients: clinical trial phase I.

Background: Exosome administration is a novel medical approach that promises excellent immunomodulatory properties without the conventional side effects of current antitumor necrosis factor drugs and stem cells. This study aimed to assess the safety and efficacy of using mesenchymal stem cell (MSC) exosomes to treat refractory fistulas in patients with inflammatory bowel disease. Methods: MSCs were derived from the umbilical cords and their exosomes were isolated. Five patients with refractory perianal Crohn's disease fistulas with a median age of 35 years (range 31-47 years) were enrolled in the study. Exosome injections were administered in the operating room to patients with refractory fistula (fistulas that are irresponsive to anti-tumor necrosis factor-α administration within 6 months). Six months later, a physical examination, face-to-face interviews, and magnetic resonance imaging were employed to evaluate the therapy responses of patients. Results: The outcomes within 6 months after initiation of therapy showed that four patients had responded to therapy. Three patients who received exosome injections exhibited complete healing, while one reported no improvement and active discharge from the fistula site. In addition, five patients (100%) reported neither systemic nor local adverse effects. Conclusions: Injection of exosomes extracted from MSCs demonstrates safety and a satisfactory therapeutic effect, as evidenced in this and other studies, and may play a significant role in the future treatment of gastrointestinal fistulas.

Design and fabrication of modified bi-layer poly vinyl alcohol adhesive sealant film for preventing gastrointestinal leakage.

Anastomosis leakage is a common complication in gastrointestinal surgery associated with high mortality, morbidity, and cost to health care providers. According to the significant burdens of AL, several methods have been introduced to overcome this problem. Despite the crucial complications of the AL, current approaches, including glue-based adhesives and bio-based sealants, have certain disadvantages and newly gained attractions for solving this challenge. This study focused on fabricating a sealant structure based on poly (vinyl alcohol) film patterned with gelatin particles and evaluating for prevention of AL. Here, we used a 3D printed model for dry spraying gelatin particles in a random and oriented pattern on PVA films. The mechanical and adhesion properties of both types of films were assessed further, and the efficacy of the novel sealant was evaluated in vivo. The results revealed that the film with an oriented pattern provided better adhesive and mechanical properties, expression of anti-inflammatory cytokines, and collagen deposition. In conclusion, our novel sealant enhanced mechanical features and the healing process of gastrointestinal surgical anastomosis and can be considered a novel method for the prevention of AL.

Decellularized human amniotic membrane reinforced by MoS2-Polycaprolactone nanofibers, a novel conductive scaffold for cardiac tissue engineering.

In order to regenerate myocardial tissues with functional characteristics, we need to copy some properties of the myocardium, such as its extracellular matrix and electrical conductivity. In this study, we synthesized nanosheets of Molybdenum disulfide (MoS2), and integrated them into polycaprolactone (PCL) and electrospun on the surface of decellularized human amniotic membrane (DHAM) with the purpose of improving the scaffolds mechanical properties and electrical conductivity. For in vitro studies, we seeded the mouse embryonic cardiac cells, mouse Embryonic Cardiac Cells (mECCs), on the scaffolds and then studied the MoS2 nanocomposites by scanning electron microscopy and Raman spectroscopy. In addition, we characterized the DHAM/PCL and DHAM/PCL-MoS2 by SEM, transmission electron microscopy, water contact angle measurement, electrical conductivity, and tensile test. Besides, we confirmed the scaffolds are biocompatible by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT assay. Furthermore, by means of SEM images, it was shown that mECCs attached to the DHAM/PCL-MoS2 scaffold have more cell aggregations and elongated morphology. Furthermore, through the Real-Time PCR and immunostaining studies, we found out cardiac genes were maturated and upregulated, and they also included GATA-4, c-TnT, NKX 2.5, and alpha-myosin heavy chain in cells cultured on DHAM/PCL-MoS2 scaffold in comparison to DHAM/PCL and DHAM. Therefore, in terms of cardiac tissue engineering, DHAM nanofibrous scaffolds reinforced by PCL-MoS2 can be suggested as a proper candidate.

Mesenchymal Stem/Stromal Cells Overexpressing CXCR4R334X Revealed Enhanced Migration: A Lesson Learned from the Pathogenesis of WHIM Syndrome.

C-X-C chemokine receptor type 4 (CXCR4), initially recognized as a co-receptor for HIV, contributes to several disorders, including the WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. CXCR4 binds to its ligand SDF-1 to make an axis involved in the homing property of stem cells. This study aimed to employ WHIM syndrome pathogenesis as an inspirational approach to reinforce cell therapies. Wild type and WHIM-type variants of the CXCR4 gene were chemically synthesized and cloned in the pCDH-513B-1 lentiviral vector. Molecular cloning of the synthetic genes was confirmed by DNA sequencing, and expression of both types of CXCR4 at the protein level was confirmed by western blotting in HEK293T cells. Human adipose-derived mesenchymal stem cells (Ad-MSCs) were isolated, characterized, and subjected to lentiviral transduction with Wild type and WHIM-type variants of CXCR4. The presence of copGFP-positive MSCs confirmed the high efficiency of transduction. The migration ability of both groups of transduced cells was then assessed by transwell migration assay in the presence or absence of a CXCR4-blocking agent. Our qRT-PCR results showed overexpression of CXCR4 at mRNA level in both groups of transduced MSCs, and expression of WHIM-type CXCR4 was significantly higher than Wild type CXCR4 (P<0.05). Our results indicated that the migration of genetically modified MSCs expressing WHIM-type CXCR4 had significantly enhanced towards SDF1 in comparison with Wild type CXCR4 (P<0.05), while it was reduced after treatment with CXCR4 antagonist. These data suggest that overexpression of WHIM-type CXCR4 could lead to enhanced and sustained expression of CXCR4 on human MSCs, which would increase their homing capability; hence it might be an appropriate strategy to improve the efficiency of cell-based therapies.

Cartilage tissue engineering by co-transplantation of chondrocyte extracellular vesicles and mesenchymal stem cells, entrapped in chitosan-hyaluronic acid hydrogel.

Mesenchymal stem cells (MSCs) on injectable hydrogels are mostly used to regenerate articular cartilage, which would have a variety of outcomes. Chondrocyte extracellular vesicles (EVs) have attracted many attentions for their chondrogenic differentiation capacity; however, the roles of EVs in both chondrogenic differentiation of MSCs and cartilage regeneration are poorly understood yet. In the current study, to investigate the differentiation effects of human articular chondrocyte EVs on adipose-derived MSCs, they were cultured in injectable chitosan-hyaluronic acid (CS-HA) hydrogel and then treated with chondrocyte EVs for 21 days. The continuous treatment of EVs performed on MSCs increased chondrogenic genes' expressions ofSOX9andCOL2A1and induced expression of Col II protein. In addition, glycosaminoglycans secretion was detected in the EV-treated MSCs after about 14 days. The therapeutic efficiency of this hydrogel and EVs was studied in a rabbit osteochondral defect model. MRI results revealed that the cartilage regeneration capacity of EV-treated MSCs with CS-HA hydrogel was greater than the untreated MSCs or the EV-treated MSCs without hydrogel. Moreover, histological results showed hyaline-like cartilage in the CS-HA/MSC and CS-HA/EV/MSC groups in the cartilage defect sites. These findings suggested that the chondrocyte-EVs and CS-HA hydrogel could provide the preferable niche for chondrogenic differentiation of MSCs and cartilage regeneration in osteoarthritis cartilage injuries.

Microfluidic-Based Droplets for Advanced Regenerative Medicine: Current Challenges and Future Trends.

Microfluidics is a promising approach for the facile and large-scale fabrication of monodispersed droplets for various applications in biomedicine. This technology has demonstrated great potential to address the limitations of regenerative medicine. Microfluidics provides safe, accurate, reliable, and cost-effective methods for encapsulating different stem cells, gametes, biomaterials, biomolecules, reagents, genes, and nanoparticles inside picoliter-sized droplets or droplet-derived microgels for different applications. Moreover, microenvironments made using such droplets can mimic niches of stem cells for cell therapy purposes, simulate native extracellular matrix (ECM) for tissue engineering applications, and remove challenges in cell encapsulation and three-dimensional (3D) culture methods. The fabrication of droplets using microfluidics also provides controllable microenvironments for manipulating gametes, fertilization, and embryo cultures for reproductive medicine. This review focuses on the relevant studies, and the latest progress in applying droplets in stem cell therapy, tissue engineering, reproductive biology, and gene therapy are separately evaluated. In the end, we discuss the challenges ahead in the field of microfluidics-based droplets for advanced regenerative medicine.

Comparison the effects of hypoxia-mimicking agents on migration-related signaling pathways in mesenchymal stem cells.

Adipose-derived mesenchymal stem cells (Ad-MSCs) have been designated as the promising agents for clinical applications for easy accessibility, multi-linage differentiation and immunomodulation capacity. Despite this, optimal cell delivery conditions have remained as a clinical challenge and improvement of stem cell homing to the target organs is being considered as a major strategy in cell therapy systemic injection. It has been shown that homing of mesenchymal stem cells are increased when treated with physical or chemical hypoxia-mimicking factors, however, efficiency of different agents remained to be determined. In this study, hypoxia-mimicking agents, including valproic acid (VPA), cobalt chloride (CoCl2) and deferoxamine (DFX) were examined to determine whether they are able to activate signaling molecules involved in migration of Ad-MSCs in vitro. We report that Ad-MSCs treated by DFX resulted in a significantly enhanced mRNA expression of MAPK4 (associated with MAPK signaling pathway), INPP4B (associated with Inositol polyphosphate pathway), VEGF-A and VEGF-C (associated with cytokine-cytokine receptor pathways), IL-8 and its receptor, CXCR2 (associated with IL-8 signaling pathway). While the cells treated with VPA did not show such effects and CoCl2 only upregulated VEGF-A and VEGF-C gene expression. Furthermore, results of wound-healing assays showed migration capacity of Ad-MSCs treated with DFX significantly increased 8 and 24 h of the treatment. This study provides credible evidence around DFX, which might be an effective drug for pharmacological preconditioning of Ad-MSCs to boost their homing capacity and regeneration of damaged tissues though, activation of the migration-related signaling pathways.

Incorporation of SPION-casein core-shells into silk-fibroin nanofibers for cardiac tissue engineering.

Mimicking the structure of extracellular matrix (ECM) of myocardium is necessary for fabrication of functional cardiac tissue. The superparamagnetic iron oxide nanoparticles (SPIONs, Fe3 O4 ), as new generation of magnetic nanoparticles (NPs), are highly intended in biomedical studies. Here, SPION NPs (1 wt%) were synthesized and incorporated into silk-fibroin (SF) electrospun nanofibers to enhance mechanical properties and topography of the scaffolds. Then, the mouse embryonic cardiac cells (ECCs) were seeded on the scaffolds for in vitro studies. The SPION NPs were studied by scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM). SF nanofibers were characterized after incorporation of SPIONs by SEM, TEM, water contact angle measurement, and tensile test. Furthermore, cytocompatibility of scaffolds was confirmed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. SEM images showed that ECCs attached to the scaffolds with elongated morphologies. Also, the real-time PCR and immunostaining studies approved upregulation of cardiac functional genes in ECCs seeded on the SF/SPION-casein scaffolds including GATA-4, cardiac troponin T, Nkx 2.5, and alpha-myosin heavy chain, compared with the ones in SF. In conclusion, incorporation of core-shells in SF supports cardiac differentiation, while has no negative impact on ECCs' proliferation and self-renewal capacity.

Adipocyte lineage differentiation potential of MSCs isolated from reaming material.

Mesenchymal stem cells (MSCs) obtained from various sources have been used for different therapeutic applications including tissue regeneration. Reamer/irrigator/aspirator (RIA) has been increasingly used in recent years for the derivation of MSCs. Here in this investigation we have comparatively analyzed MSCs obtained from iliac crest bone marrow (ICBM) and RIA for their morphology, cluster determinant (CD) markers, and adipogenic differentiation capacity. MSCs were isolated, cultured, and purified from both sources and then flow cytometric studies were performed to study their characteristics. The differentiation potential of RIA and ICBM was examined by an Oil Red O staining protocol. Moreover, the tissue-specific markers related to adipogenesis were analyzed by real-time polymerase chain reaction (RT-PCR). The cells were cultured in the relevant induction medium and then adipogenic lineage differentiation was tested and confirmed for all MSC preparations. Additionally, analysis by flow cytometer was indicative of RIA derived MSCs (RIA-MSCs) having a more homogenous population than ICBM derived MSCs. The RIA-MSCs differentiation toward adipogenic lineage was more efficient compared with ICBM-MSCs. Direct comparative analysis of RIA to ICBM-MSCs indicated that the RIA-MSCs had a higher potential toward adipocyte lineage differentiation compared with ICBM-MSCs.

Bone defect healing is induced by collagen sponge/polyglycolic acid.

We have evaluated the capability of a collagen/poly glycolic acid (PGA) scaffold in regeneration of a calvarial bone defects in rabbits. 4 bone critical size defects (CSD) were created in the calvarial bone of each rabbit. The following 4 treatment modalities were tested (1) a collagen/PGA scaffold (0.52% w/w); (2) the collagen/PGA scaffold (0.52% w/w) seeded with adipose-derived mesenchymal stem cells (AD-MSCs, 1 × 106 cells per each defect); (3) AD-MSCs (1 × 106 cells) no scaffold material, and (4) blank control. The rabbits were then divided into 3 random groups (of 5) and the treatment outcomes were evaluated at 4, 8 and 12 weeks. New bone formation was histologically assessed. Experimental groups were analyzed by CT scan and real-time PCR. Histological analysis of bone defects treated with collagen/PGA alone exhibited significant fibrous connective tissue formation at the 12 weeks of treatments (P ≤ 0.05). There was no significant difference between collagen/PGA alone and collagen/PGA + AD-MSCs groups. The results were confirmed by CT scan data showing healing percentages of 34.20% for the collage/PGA group alone as compared to the control group and no difference with collagen/PGA containing AD-MSCs (1 × 106 cells). RT-PCR analysis also indicated no significant differences between collagen/PGA and collagen/PGA + AD-MSC groups, although both scaffold containing groups significantly express ALP and SIO rather than groups without scaffolds. Although there was no significant difference between the scaffolds containing cells with non-cellular scaffolds, our results indicated that the Collagen/PGA scaffold itself had a significant effect on wound healing as compared to the control group. Therefore, the collagen/PGA scaffold seems to be a promising candidate for research in bone regeneration.

Augmented migration of mesenchymal stem cells correlates with the subsidiary CXCR4 variant.

Use of mesenchymal stem cells (MSCs) has been introduced as a promising tool, for structural and functional recovery of damaged tissues/organs. Studies have indicated that interactions between chemokine receptors and their ligands have a critical role in homing of MSCs to the site of injury. Although CXCR4 variants have been characterized, the exact role of each transcript in homing has remained unclear. In this study, cells were pretreated with various hypoxia-mimicking compounds (valproic acid, cobalt-chloride, and deferoxamine mesylate). Results indicated that both variants of CXCR4 were overexpressed after 24 hours of treatments and their expression could cooperatively induce and promote the cell migration. Moreover, deferoxamine mesylate was more effective in overexpression of variant A (lo), which resulted in higher level of CXCR4 protein and the highest rate of migration of the cells. In conclusion, our findings may have important potential implications in clinical applications, reinforcing the concept that manipulating the expression of specific CXCR4 variants may increase migration of MSCs.

Long bone mesenchymal stem cells (Lb-MSCs): clinically reliable cells for osteo-diseases.

Mesenchymal stem cells (MSCs) have been designated as the most reliable cells in clinics to treat osteo-diseases because of their versatile nature. MSCs, isolated from long bone (Lb-MSCs) are rarely reported and named as RIA-MSCs because of the reamer-irrigator-aspirator (RIA) device. The potential of these cells in the treatment of non-union bone fractures made them the ideal candidates to be studied for clinical practices. In this work, effect of cryopreservation on the proliferation and differentiation capabilities of long bone MSCs (Lb-MSCs) has been studied. For this purpose, Lb-MSCs were isolated via RIA device and characterized using flow cytometry and differentiation assays. Cells were cryopreserved for 3, 6 and 12 months and thereafter were characterized using differentiation assays and genetic markers specific for osteogenic, chondrogenic, and adipogenic potential quantitatively by qRT-PCR. Lb-MSCs were found expressing MSC characteristic markers defining their identity. The population doubling time (PDT) was about 2.5 ± 0.5 days and colonies appeared after 7-10 days. Differentiation potential and gene expression of 3, 6 and 12 months cryopreserved Lb-MSCs were unaltered. The results show that cryopreservation did not have an effect on the differentiation potential of human Lb-MSCs. Therefore, our work offers Lb-MSCs as clinically cells for treating osteo-diseases.

Chemokine Receptors Expression in MSCs: Comparative Analysis in Different Sources and Passages.

MSC-based therapy is providing a cure for degenerative diseases with unmet medical need and usually iliac crest bone marrow (ICBM) are being applied in clinics. Alternative sources, including adipose tissue and reamer/irrigator/aspirator hold great potential for isolating MCSs. Here, we compared original MSCs features of adipose tissue (Ad-MSCs) and bone marrow of long-bone (RIA-MSCs) or iliac crest, and the expression of chemokine receptors (including CXCR4, CX3CR1, CXCR6, CXCR2, CCR1 and CCR7) in these three sources, which are important in the context of homing. We further investigated the role of SDF-1/CXCR4 axis as a key player in motility of different population of MSCs using Transwell migration assay. All cells exhibited typical MSCs characteristics. However, different MSCs sources expressed different levels of chemokine receptors. Generally, the expression of these chemokine receptors was decreased with increasing passage (P) number from 2 to 3. Interestingly, it was observed that the CXCR4 expression and migration capacity in Ad-MSCs is significantly higher than ICBM and RIA-MSCs in P2. Although our data showed that CXCR4 had highest expression in P2 Ad-MSCs, but it dramatically declined following sub-culturing in the P3. Hence, to improve homing of MSCs by means of chemokine/their receptors axis, the source of isolation and passage number should be considered for clinical applications.

PGA-incorporated collagen: Toward a biodegradable composite scaffold for bone-tissue engineering.

Nowadays composite scaffolds based on synthetic and natural biomaterials have got attention to increase healing of non-union bone fractures. To this end, different aspects of collagen sponge incorporated with poly(glycolic acid) (PGA) fiber were investigated in this study. Collagen solution (6.33 mg/mL) with PGA fibers (collagen/fiber ratio [w/w]: 4.22, 2.11, 1.06, 0.52) was freeze-dried, followed by dehydrothermal cross-linking to obtain collagen sponge incorporating PGA fibers. Properties of scaffold for cell viability, proliferation, and differentiation of mesenchymal stem cells (MSCs) were evaluated. Scanning electron microscopy showed that collagen sponge exhibited an interconnected pore structure with an average pore size of 190 µm, irrespective of PGA fiber incorporation. The collagen-PGA sponge was superior to the original collagen sponge in terms of the initial attachment, proliferation rate, and osteogenic differentiation of the bone marrow-MSCs (BM-MSC). The shrinkage of sponges during cell culture was significantly suppressed by fiber incorporation. Incorporation of PGA fiber is a simple and promising way to reinforce collagen sponge without impairing biocompatibility. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2020-2028, 2016.

Chemically primed bone-marrow derived mesenchymal stem cells show enhanced expression of chemokine receptors contributed to their migration capability.

OBJECTIVES: The limited homing potential of bone-marrow-derived mesenchymal stem cells (BM-MSC) is the key obstacle in MSC-based therapy. It is believed that chemokines and chemokine receptor interactions play key roles in cellular processes associated with migration. Meanwhile, MSCs express a low level of distinct chemokine receptors and they even lose these receptors on their surface after a few passages which influence their therapeutic applications negatively. This study investigated whether treatment of BM-MSCs with hypoxia-mimicking agents would increase expression of some chemokine receptors and cell migration. MATERIALS AND METHODS: BM-MSCs were treated at passage 2 for our gene expression profiling. All qPCR experiments were performed by SYBR Green method in CFX-96 Bio-Rad Real-Time PCR. The Boyden chamber assay was utilized to investigate BM-MSC homing. RESULTS: Possible approaches to increasing the expression level of chemokine receptors by different hypoxia-mimicking agents such as valproic acid (VPA), CoCl2, and desferrioxamine (DFX) are described. Results show DFX efficiently up-regulate the CXCR7 and CXCR4 gene expression while VPA increase only the CXCR7 gene expression and no significant change in expression level of CXCR4 and the CXCR7 gene was detectable by CoCl2 treatment. Chemotaxis assay results show that pre-treatment with DFX, VPA, and Cocl2 enhances significantly the migration ability of BM-MSCs compared with the untreated control group and DFX treatment accelerates MSCs homing significantly with a higher rate than VPA and Cocl2 treatments. CONCLUSION: Our data supports the notion that pretreatment of MSC with VPA and DFX improves the efficiency of MSC therapy by triggering homing regulatory signaling pathways.