Reduced graphene oxide-incorporated calcium phosphate cements with pulsed electromagnetic fields for bone regeneration.

Natural calcium phosphate cements (CPCs) derived from sintered animal bone have been investigated to treat bone defects, but their low mechanical strength remains a critical limitation. Graphene improves the mechanical properties of scaffolds and promotes higher osteoinduction. To this end, reduced graphene oxide-incorporated natural calcium phosphate cements (RGO-CPCs) are fabricated for reinforcement of CPCs' characteristics. Pulsed electromagnetic fields (PEMFs) were additionally applied to RGO-CPCs to promote osteogenic differentiation ability. The fabricated RGO-CPCs show distinct surface properties and chemical properties according to the RGO concentration. The RGO-CPCs' mechanical properties are significantly increased compared to CPCs owing to chemical bonding between RGO and CPCs. In in vitro studies using a mouse osteoblast cell line and rat-derived adipose stem cells, RGO-CPCs are not severely toxic to either cell type. Cell migration study, western blotting, immunocytochemistry, and alizarin red staining assay reveal that osteoinductivity as well as osteoconductivity of RGO-CPCs was highly increased. In in vivo study, RGO-CPCs not only promoted bone ingrowth but also enhanced osteogenic differentiation of stem cells. Application of PEMFs enhanced the osteogenic differentiation of stem cells. RGO-CPCs with PEMFs can overcome the flaws of previously developed natural CPCs and are anticipated to open the gate to clinical application for bone repair and regeneration.

Development and characterization of waste equine bone-derived calcium phosphate cements with human alveolar bone-derived mesenchymal stem cells.

Calcium phosphate cements (CPCs) are regarded as promising graft substitutes for bone tissue engineering. However, their wide use is limited by the high cost associated with the complex synthetic processes involved in their fabrication. Cheaper xenogeneic calcium phosphate (CaP) materials derived from waste animal bone may solve this problem. Moreover, the surface topography, mechanical strength, and cellular function of CPCs are influenced by the ratio of micro- to nano-sized CaP (M/NCaP) particles. In this study, we developed waste equine bone (EB)-derived CPCs with various M/NCaP particle ratios to examine the potential capacity of EB-CPCs for bone grafting materials. Our study showed that increasing the number of NCaP particles resulted in reductions in roughness and porosity while promoting smoother surfaces of EB-CPCs. Changes in the chemical properties of EB-CPCs by NCaP particles were observed using X-ray diffractometry. The mechanical properties and cohesiveness of the EB-CPCs improved as the NCaP particle content increased. In an in vitro study, EB-CPCs with a greater proportion of MCaP particles showed higher cell adhesion. Alkaline phosphatase activity indicated that osteogenic differentiation by EB-CPCs was promoted with increased NCaP particle content. These results could provide a design criterion for bone substitutes for orthopedic disease, including periodontal bone defects.

Quantification of three-dimensional facial asymmetry for diagnosis and postoperative evaluation of orthognathic surgery.

BACKGROUND: To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT. METHODS: The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated. RESULTS: The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well. CONCLUSIONS: The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.

Allogeneic Fibrin Clot for Odontogenic/Cementogenic Differentiation of Human Dental Mesenchymal Stem Cells.

BACKGROUND: Fetal bovine serum is widely used as a growth supplement for cell culture medium; however, animal-borne pathogens increase the risk of transmitting infectious agents. Platelet-rich fibrin is recently considered as a successful alternative but leukocytes present limits to its allogeneic feasibility. The aim of this study was to explore the effects of allogeneic fibrin clot (AFC) without leukocytes on inducing odontogenic/cementogenic differentiation of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs) in vitro and in vivo. METHODS: AFC was prepared by high-speed centrifugation and leukocytes were almost removed, and AFC serum was obtained through three freeze-thaw cycles. hDPSCs and hPDLSCs were treated with AFC serum to investigate the odontogenic or cementogenic associated markers by real-time polymerase chain reaction. hDPSCs were treated with AFC serum and placed inside of dentin canal, hPDLSCs were treated with AFC serum to wrap outside of dentin, the mixture was then transplanted into the subcutaneous of nude mice for 12 weeks. RESULTS: AFC serum exhibited enough growth factors and cytokines to induce odontogenic/cementogenic differentiation of hDPSCs and hPDLSCs in vitro. Furthermore, AFC seurum could induce hDPSCs to differentiate into odontoblasts-like cells and pulp-like tissues, and hPDLSCs to regenerate cementum-like tissues. CONCLUSION: AFC could be an alternative safe source with growth factors for the expansion of human dental mesenchymal stem cells (hDMSCs).

MSM promotes human periodontal ligament stem cells differentiation to osteoblast and bone regeneration.

Periodontal disease is the most common chronic disease of the oral and maxillofacial region, causing alveolar bone loss and ultimate loss of tooth. The purpose of treatment of periodontal disease is to promote the regeneration of periodontal tissue, including alveolar bone, and implantation of fixtures to replace the missing tooth as a result of advanced periodontal disease also requires alveolar bone regeneration. Methylsulfonylmethane (MSM) is a sulfur compound with well-known anti-inflammatory effects but its effects on bone regeneration are unknown. In this study, we investigated the effects of MSM on osteogenic differentiation of human PDLSCs (hPDLSCs) in vitro and in vivo. Our results demonstrate that MSM not only promotes the proliferation but also promotes osteogenic differentiation of hPDLSCs. MSM increased the expression levels of osteogenic specific markers that ALP, OPN, OCN, Runx2, and OSX. Smad2/3 signaling pathway was reinforced by MSM. Runx2, which downstream of Smad pathway, was expressed in accordance. Consistent with in vitro results, in vivo calvarial defect model and transplantation model revealed that MSM induces hPDLSCs to differentiate into osteoblast, which express ALP, OPN and OCN highly and enhance bone formation. These results suggest that MSM promotes osteogenic differentiation and bone formation of hPDLSCs, and Smad2/3 / Runx2 / OSX / OPN may play critical roles in the MSM-induced osteogenic differentiation. Thus, MSM combined with hPDLSCs may be a good candidate for future clinical applications in alveolar bone regeneration and can be used for graft material in reconstructive dentistry.

JNK2 silencing and caspase-9 activation by hyperosmotic polymer inhibits tumor progression.

c-Jun N-terminal kinase 2 (JNK2) is primarily responsible for the oncogenic transformation of the transcription factor c-Jun. Expression of the proto-oncogene c-Jun progresses the cell cycle from G1 to S phase, but when its expression becomes awry it leads to uncontrolled proliferation and angiogenesis. Delivering a JNK2 siRNA (siJNK2) in tumor tissue was anticipated to reverse the condition with subsequent onset of apoptosis which predominantly requires an efficient delivering system capable of penetrating through the compact tumor mass. In the present study, it was demonstrated that polymannitol-based vector (PMGT) with inherent hyperosmotic properties was able to penetrate through and deliver the siJNK2 in the subcutaneous tumor of xenograft mice. Hyperosmotic activity of polymannitol was shown to account for the enhanced therapeutic delivery both in vitro and in vivo because of the induction of cyclooxygenase-2 (COX-2) which stimulates caveolin-1 for caveolae-mediated endocytosis of the polyplexes. Further suppression of JNK2 and hence c-Jun expression led to the activation of caspase-9 to induce apoptosis and inhibition of tumor growth in xenograft mice model. The study exemplifies PMGT as an efficient vector for delivering therapeutic molecules in compact tumor tissue and suppression of JNK2 introduces a strategy to inhibit tumor progression.

Targeted Delivery of siRNA Therapeutics using Ligand Mediated Biodegradable Polymeric Nanocarriers.

BACKGROUND: Cancer poses a major public health issue, is linked with high mortality rates across the world, and shows a strong interplay between genetic and environmental factors. To date, common therapeutics, including chemotherapy, immunotherapy, and radiotherapy, have made significant contributions to cancer treatment, although diverse obstacles for achieving the permanent "magic bullet" cure have remained. Recently, various anticancer therapeutic agents designed to overcome the limitations of these conventional cancer treatments have received considerable attention. One of these promising and novel agents is the siRNA delivery system; however, poor cellular uptake and altered siRNA stability in physiological environments have limited its use in clinical trials. Therefore, developing the ideal siRNA delivery system with low cytotoxicity, improved siRNA stability in the body's circulation, and prevention of its rapid clearance from bodily fluids, is rapidly emerging as an innovative therapeutic strategy to combat cancer. Moreover, active targeting using ligand moieties which bind to over-expressed receptors on the surface of cancer cells would enhance the therapeutic efficiency of siRNA. CONCLUSION: In this review, we provide 1) an overview of the non-viral carrier associated with siRNA delivery for cancer treatment, and 2) a description of the five major cancer-targeting ligands.

Effects of pulsing of light on the dentinogenesis of dental pulp stem cells in vitro.

Low power light (LPL) treatment has been widely used in various clinical trials, which has been known to reduce pain and inflammation and to promote wound healing. LPL was also shown to enhance differentiation of stem cells into specific lineages. However, most studies have used high power light in mW order, and there was lack of studies about the effects of very low power light in µW. In this study, we applied 810 nm LPL of 128 µW/cm2 energy density in vitro. Upon this value, continuous wave (CW) irradiation did not induce any significant changes for differentiation of human dental pulp stem cells (hDPSCs). However, the membrane hyperpolarization, alkaline phosphatase activity, and intracellular oxidative stress were largely enhanced in the pulsed wave (PW) with 30% of duty cycle and 300-3000 Hz frequencies-LPL in which LED driver work in the form of square wave. After 21 days of daily LPL treatment, Western blot revealed the dentinogenesis in this condition in vitro. This study demonstrates that the very low power light at 810 nm enhanced significant differentiation of hDPSCs in the PW mode and there were duty cycle dependency as well as pulsing frequency dependency in the efficiency.

Pulse frequency dependency of photobiomodulation on the bioenergetic functions of human dental pulp stem cells.

Photobiomodulation (PBM) therapy contributes to pain relief, wound healing, and tissue regeneration. The pulsed wave (PW) mode has been reported to be more effective than the continuous wave (CW) mode when applying PBM to many biological systems. However, the reason for the higher effectiveness of PW-PBM is poorly understood. Herein, we suggest using delayed luminescence (DL) as a reporter of mitochondrial activity after PBM treatment. DL originates mainly from mitochondrial electron transport chain systems, which produce reactive oxygen species (ROS) and adenosine triphosphate (ATP). The decay time of DL depends on the pulse frequencies of applied light, which correlate with the biological responses of human dental pulp stem cells (hDPSCs). Using a low-power light whose wavelength is 810 nm and energy density is 38 mJ/cm2, we find that a 300-Hz pulse frequency prolonged the DL pattern and enhanced alkaline phosphatase activity. In addition, we analyze mitochondrial morphological changes and their volume density and find evidence supporting mitochondrial physiological changes from PBM treatment. Our data suggest a new methodology for determining the effectiveness of PBM and the specific pulse frequency dependency of PBM in the differentiation of hDPSCs.

Extensive Surgical Procedures Result in Better Treatment Outcomes for Bisphosphonate-Related Osteonecrosis of the Jaw in Patients With Osteoporosis.

PURPOSE: To identify the risk factors associated with relapse or treatment failure after surgery for bisphosphonate-related osteonecrosis of the jaw (BRONJ) in patients with osteoporosis. PATIENTS AND METHODS: We performed a retrospective cohort study of BRONJ in patients with osteoporosis who had undergone surgical procedures from 2004 to 2016 at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. The predictor variables were a set of heterogeneous variables, including demographic (age, gender), anatomic (maxilla or mandible, or both, affected location), clinical (disease stage, etiology, comorbidities, history of intravenous bisphosphonate intake), time (conservative treatment before surgery, bisphosphonate treatment before the development of BRONJ, discontinuation of the drug before surgery, interval to final follow-up, interval to reoperation in the case of relapse or treatment failure), and perioperative variables (type of anesthesia, type of surgical procedures). The primary outcome variable was relapse after surgery that required reoperation (yes vs no). The descriptive and bivariate statistics were computed to assess the relationships between the study variables and the outcome. To determine the risk factors, we conducted a survival analysis using the Cox model. RESULTS: The final sample included 325 subjects with a median age of 75 years, and 97% were women. After surgery, 30% of patients did not completely recuperate and underwent repeat surgery. The interval from the first surgery to reoperation ranged from 10 days to 5.6 years. Relapse or treatment failure most often occurred immediately after surgery. The type of surgical procedure and mode of anesthesia were the most important factors in the treatment outcome. A drug holiday did not appear to influence the likelihood of relapse after surgery. CONCLUSIONS: Treatment of BRONJ in patients with osteoporosis might benefit from more careful and extensive surgical procedures rather than curettage performed with the patient under local anesthesia.

Physical Stimulation-Based Osteogenesis: Effect of Secretion In Vitro on Fluid Dynamic Shear Stress of Human Alveolar Bone-Derived Mesenchymal Stem Cells.

Human alveolar bone-derived mesenchymal stem cells (hABMSCs) are promising candidates for bone therapies, which have the capacity to differentiate into osteoblasts. Recently, secretion of inducible cytokines and growth factors from mesenchymal stem cells (MSCs) has been discovered, and we also have reported the osteogenic effects of cell physical stimulation. In this study, we investigated the effects of hABMSCs-conditioned secretion media (B-CSM) on osteogenic differentiation of hABMSCs in vitro. Furthermore, we analyzed the B-CSM by proteomics array to identify inducible factors which facilitate osteogenic differentiation. To determine optimal concentration, B-CSM was firstly added at varying amounts (5, 10, 20, 40, and 60%) relative to culture medium. The viability and proliferation of hABMSCs were higher after treating with 5-20% B-CSM to the cells, compared to 40-60%. In addition, the expression of stem cells markers CD146 and STRO-1 was increased in the cells treated with 5-20% B-CSM, but decreased with 40-60%. We also found that B-CSM promoted osteogenic differentiation of hABMSCs such as mineralized nodules were strongly generated by 5-20%. B-CSM was most effective in increasing the expression of Vinculin and osteocalcin (OCN) in osteogenic differentiation of hABMSCs. Taken together, the results of our study ultimately indicate that B-CSM from hABMSCs induced by physical stimulation induce the proliferation and osteogenic differentiation of hABMSCs.

Pulsed-Electromagnetic-Field-Assisted Reduced Graphene Oxide Substrates for Multidifferentiation of Human Mesenchymal Stem Cells.

Electromagnetic fields (EMFs) can modulate cell proliferation, DNA replication, wound healing, cytokine expression, and the differentiation of mesenchymal stem cells (MSCs). Graphene, a 2D crystal of sp(2) -hybridized carbon atoms, has entered the spotlight in cell and tissue engineering research. However, a combination of graphene and EMFs has never been applied in tissue engineering. This study combines reduced graphene oxide (RGO) and pulsed EMFs (PEMFs) on the osteogenesis and neurogenesis of MSCs. First, the chemical properties of RGO are measured. After evaluation, the RGO is adsorbed onto glass, and its morphological and electrical properties are investigated. Next, an in vitro study is conducted using human alveolar bone marrow stem cells (hABMSCs). Their cell viability, cell adhesion, and extracellular matrix (ECM) formation are increased by RGO and PEMFs. The combination of RGO and PEMFs enhances osteogenic differentiation. Together, RGO and PEMFs enhance the neurogenic and adipogenic differentiation of hABMSCs. Moreover, in a DNA microarray analysis, the combination of RGO and PEMFs synergically increases ECM formation, membrane proteins, and metabolism. The combination of RGO and PEMFs is expected to be an efficient platform for stem cell and tissue engineering.

Recombinant Human Plasminogen Activator Inhibitor-1 Accelerates Odontoblastic Differentiation of Human Stem Cells from Apical Papilla.

Dental caries, the most prevalent oral disease in dental patients, involves the phases of demineralization and destruction of tooth hard tissues like enamel, dentin, and cementum. Dentin is a major component of the root and is also the innermost layer that protects the tooth nerve, exposure of which results in pain. In this study, we used human stem cells from apical papilla (hSCAP), which are early progenitor cells, to examine the effects of recombinant human plasminogen activator inhibitor-1 (rhPAI-1) on odontogenic differentiation in vitro and in vivo. We demonstrated that rhPAI-1 promoted the proliferation and odontogenic differentiation of hSCAP and increased the expression levels of odontoblast-associated markers. We also observed that rhPAI-1 upregulated the expression of Smad4, nuclear factor I-C (NFI-C), Runx2, and osterix (OSX) during odontogenic differentiation. Notably, transplantation of rhPAI-1-treated hSCAP effectively induced odontoblastic differentiation and dentinal formation. And the differentiated odontoblast-like cells showed numerous odontoblast processes inserted in dentin tubules and arranged collagen fibers. Furthermore, odontoblast-associated markers were more highly expressed in the rhPAI-1-induced differentiated odontoblast-like cells compared with the control group. These markers were also more highly expressed in the newly formed dentin-like tissue of the rhPAI-1-treated group compared with the control group. Consistent with our in vitro results, the expression levels of Smad4, NFI-C, and OSX were also increased in the rhPAI-1-treated group compared with the control group. Taken together, these results suggest that rhPAI-1 promotes odontoblast differentiation and dentin formation of hSCAP, and Smad4/NFI-C/OSX may play critical roles in the rhPAI-1-induced odontogenic differentiation. Thus, dental stem cells from apical papilla combined with rhPAI-1 could lead to dentin regeneration in clinical implications.

Monolayer Graphene-Directed Growth and Neuronal Differentiation of Mesenchymal Stem Cells.

The development of an efficient platform for the growth and neuronal differentiation of stem cells is crucial for autologous cell therapy and tissue engineering to treat various neuronal disorders and neurodegenerative diseases. In this study, we describe the use of highly uniform graphene platforms that provide unique environments where unusual three-dimensional spheroids of human mesenchymal stem cells (hMSCs) are formed, which is advantageous for the differentiation of hMSCs into neurons. We suppose that graphene regulates the interactions at cell-substrate or cell-cell interfaces, consequently promoting the neurogenesis of hMSCs as well as the outgrowth of neurites, which was evidenced by the graphene-induced upregulation of early neurogenesis-related genes. We also demonstrated that the differentiated neurons from hMSCs on graphene are notably sensitive to external ion stimulation, and their neuronal properties can be maintained even after detaching and re-seeding onto a normal cell culture substrate, suggesting the enhanced maturity of resulting neuronal cells. Thus, we conclude that monolayer graphene is capable of regulating the growth and neural differentiation of hMSCs, which would provide new insight and strategy not only for autologous stem cell therapy but for tissue engineering and regenerative medicine based on graphene scaffolds.

Nanoparticle-mediated delivery of siRNA for effective lung cancer therapy.

Lung cancer is one of the most lethal diseases worldwide, and the survival rate is less than 15% even after the treatment. Unfortunately, chemotherapeutic treatments for lung cancer are accompanied by severe side effects, lack of selectivity and multidrug resistance. In order to overcome the limitations of conventional chemotherapy, nanoparticle-mediated RNA interference drugs represent a potential new approach due to selective silencing effect of oncogenes and multidrug resistance related genes. In this review, we provide recent advancements on nanoparticle-mediated siRNA delivery strategies including lipid system, polymeric system and rigid nanoparticles for lung cancer therapies. Importantly, codelivery of siRNA with conventional anticancer drugs and recent theranostic agents that offer great potential for lung cancer therapy is covered.

Recombinant Human Plasminogen Activator Inhibitor-1 Promotes Cementogenic Differentiation of Human Periodontal Ligament Stem Cells.

The periodontium, consisting of gingiva, periodontal ligament (PDL), cementum, and alveolar bone, is necessary for the maintenance of tooth function. Specifically, the regenerative abilities of cementum with inserted PDL are important for the prevention of tooth loss. Periodontal ligament stem cells (PDLSCs), which are located in the connective tissue PDL between the cementum and alveolar bone, are an attractive candidate for hard tissue formation. We investigated the effects of recombinant human plasminogen activator inhibitor-1 (rhPAI-1) on cementogenic differentiation of human PDLSCs (hPDLSCs) in vitro and in vivo. Untreated and rhPAI-1-treated hPDLSCs mixed with hydroxyapatite/tricalcium phosphate (HA/TCP) and dentin matrix were transplanted subcutaneously into the dorsal surface of immunocompromised mice to assess their capacity for hard tissue formation at 8 and 10 weeks posttransplantation. rhPAI-1 accelerated mineral nodule formation and increased the mRNA expression of cementoblast-associated markers in hPDLSCs. We also observed that rhPAI-1 upregulated the levels of osterix (OSX) and cementum protein 1 (CEMP1) through Smad2/3 and p38 pathways, whereas specific inhibitors of Smad3 and p38 inhibited the enhancement of mineralization of hPDLSCs by rhPAI-1. Furthermore, transplantation of hPDLSCs with rhPAI-1 showed a great ability to promote cementogenic differentiation. Notably, rhPAI-1 induced hPDLSCs to regenerate cementum-like tissue with PDL fibers inserted into newly formed cementum-like tissue. These results suggest that rhPAI-1 may play a key role in cementogenic differentiation of hPDLSCs. rhPAI-1 with hPDLSCs may be a good candidate for future clinical applications in periodontal tissue regeneration and possibly in tooth root bioengineering.

Topographical extracellular matrix cues on anticancer drug-induced cytotoxicity in stem cells.

In recent years, cell chip-based platforms have begun to show promise as a means of corroborating the findings of in vivo animal tests for cytotoxicity, and perhaps in the future partially replacing the need for such animal models. In contrast to the conventional culture methods, micro- and nanofabrication techniques can be utilized to provide a set of mechanostimulatory signals to the cells that mimic the context of extracellular matrix (ECM) of the tissue in which a particular cell line resides. Here, we report periodic lateral topographic striations, with a pitch ranging approximately from 200 to 800 nm with an intention to mimic a common geometry of fibrils in the ECM such as collagen or elastin, as a platform for investigating anticancer drug-induced cytotoxicity in stem cells. The ECM cues could facilitate perimeter, elongation, and gap junction formation of mesenchymal stem cells (MSCs), which eventually influenced the fate of cells in terms of death and survival against the common chemotherapeutic agent cisplatin. Interestingly, the appropriate inhibition of gap junctions of MSCs on the ECM mimicking substrates could prevent the cisplatin-induced cytotoxicity through the inhibition of the cisplatin-induced 'death signal communication' as compared to that on the flat substrates. Our results imply that nanoscale topography is an important consideration for chip-based cytotoxicity assays, which uniquely enable the consideration and rational design of ECM-like topographic features, and furthermore, that the natural topography of the ECM in the context of stem cell niches may serve as an important indicator for chemotherapeutic agent sensitivity.

Enhanced chitosan-DNA interaction by 2-acrylamido-2-methylpropane coupling for an efficient transfection in cancer cells.

Gene therapy is the treatment of human disorders by the introduction of genetic material to specific target cells of a patient. Chitosan and its derivatives show excellent biological properties including biocompatibility, biodegradability and nonallergenicity. Primary amines of chitosan are responsible for its cationic nature and hence binding and protection of DNA for intracellular delivery. But the transfection efficiency of chitosan based gene transporters is severely hampered by its poor physical properties such as low water solubility and high viscosity. In this study, primary amines of low molecular weight (LMW) chitosan were coupled with 2-acrylamido-2-methylpropane sulphonic acid (AMP) making it water soluble for its application in gene delivery. AMP modified chitosan (CSAMP) showed an enhanced interaction with DNA and a higher buffering capacity due to AMP amines leading to a higher transfection efficiency in cancer cells (A549, HeLa and HepG2) compared to native chitosan and Lipofectamine®. In vivo studies in Balb/c through intravenous injection demonstrated a higher luciferase expression compared to LMW chitosan.

Multiscale patterned transplantable stem cell patches for bone tissue regeneration.

Stem cell-based therapy has been proposed as an enabling alternative not only for the treatment of diseases but also for the regeneration of tissues beyond complex surgical treatments or tissue transplantation. In this study, we approached a conceptual platform that can integrate stem cells into a multiscale patterned substrate for bone regeneration. Inspired by human bone tissue, we developed hierarchically micro- and nanopatterned transplantable patches as synthetic extracellular matrices by employing capillary force lithography in combination with a surface micro-wrinkling method using a poly(lactic-co-glycolic acid) (PLGA) polymer. The multiscale patterned PLGA patches were highly flexible and showed higher tissue adhesion to the underlying tissue than did the single nanopatterned patches. In response to the anisotropically multiscale patterned topography, the adhesion and differentiation of human mesenchymal stem cells (hMSCs) were sensitively controlled. Furthermore, the stem cell patch composed of hMSCs and transplantable PLGA substrate promoted bone regeneration in vivo when both the micro- and nanotopography of the substrate surfaces were synergistically combined. Thus, our study concludes that multiscale patterned transplantable stem cell patches may have a great potential for bone regeneration as well as for various regenerative medicine approaches.

Nucleotide biosynthesis arrest by silencing SHMT1 function via vitamin B6-coupled vector and effects on tumor growth inhibition.

Serine hydroxymethyltransferase isoforms (SHMT1 & SHMT2α), which serve as scaffold protein for the formation of a multi-enzyme complex and generate one-carbon unit for the de novo thymidylate biosynthesis pathway during DNA synthesis, are vitamin B6 (VB6)-dependent enzyme. Cancer cells with high proliferation intensity need increased SHMT activation which enforces the facilitated-diffusion of VB6 for the continuous functioning of thymidylate synthase cycle. Therefore, SHMT knockdown presents an alternative approach to prevent DNA synthesis in cancer cells; however, its potential to inhibit cancer growth remains unknown so far. Here we demonstrated that VB6 coupled to poly(ester amine) (VBPEA) enforces a high level of VTC (VB6-transporting membrane carriers)-mediated endocytosis of the complexed SHMT1 siRNA (siSHMT1) to interrupt the thymidylate biosynthesis pathway of cancer cells. The detrimental effect of SHMT1 knockdown on the disintegration of multi-enzyme complex resulted in cell cycle arrest and a decrease in cell's genomic DNA content, leading to enhanced apoptotic events in cancer cells. A reduction in tumor size was observed with constant SHMT1 suppression in xenograft mice. This study illustrates how silencing the SHMT1 expression inhibits cancer growth and the increased VB6 channeling for sustenance of cancer cells promotes VB6-coupled vector to elicit enhanced delivery of siSHMT1.