Delivery Of Mesenchymal Stem Cells Research Articles

Intravascular cell therapy in stroke: predicting the future trends.

This short review examines the trends that have taken place during the last two decades in selecting delivery route and cell product in confirmatory preclinical stroke research. If there had been a major change, this might indicate a strategy with a high potential to enter early-phase clinical studies. The retrospective data show that intravenous cell delivery of mesenchymal stem cells remains the most popular approach in experimental research, clearly dominating early phase clinical studies. The advantages and risks of current practices are discussed in the hope that these will improve translational success and accelerate clinical development of safe and efficient cell products.

Mesenchymal Stem Cell Therapy for Ischemic Heart Disease: Advances and Challenges.

Ischemic Heart Disease (IHD) has been recognized as the main cause of mortality in the modern world. Application of cell therapy technologies for the IHD treatment has been actively studied from the beginning of 2000s. The review is dedicated to the use of mesenchymal stem cells (MSC) in the therapy of IHD. The strategies of the MSC modification in vitro for improvement of their regenerative potential are extensively discussed, including preconditioning to enhance the cell survival, boosting their paracrine effect and manipulating their cardiomyogenic differentiation. The optimization of the MSC delivery and opportunities related to the use of biomaterials as cell carriers are also discussed. The results of the most important clinical studies on the MSC-based IHD therapy are presented, including those completed and published in the literature and the ongoing clinical trials registered at clinicaltrials.gov by June 2018.

Silk/Fibroin Microcarriers for Mesenchymal Stem Cell Delivery: Optimization of Cell Seeding by the Design of Experiment.

In this methodological paper, lyophilized fibroin-coated alginate microcarriers (LFAMs) proposed as mesenchymal stem cells (MSCs) delivery systems and optimal MSCs seeding conditions for cell adhesion rate and cell arrangement, was defined by a Design of Experiment (DoE) approach. Cells were co-incubated with microcarriers in a bioreactor for different time intervals and conditions: variable stirring speed, dynamic culture intermittent or continuous, and different volumes of cells-LFAMs loaded in the bioreactor. Intermittent dynamic culture resulted as the most determinant parameter; the volume of LFAMs/cells suspension and the speed used for the dynamic culture contributed as well, whereas time was a less influencing parameter. The optimized seeding conditions were: 98 min of incubation time, 12.3 RPM of speed, and 401.5 µL volume of cells-LFAMs suspension cultured with the intermittent dynamic condition. This DoE predicted protocol was then validated on both human Adipose-derived Stem Cells (hASCs) and human Bone Marrow Stem Cells (hBMSCs), revealing a good cell adhesion rate on the surface of the carriers. In conclusion, microcarriers can be used as cell delivery systems at the target site (by injection or arthroscopic technique), to maintain MSCs and their activity at the injured site for regenerative medicine.

GRAPHENE OXIDE CONTAINING CHITOSAN BASED HYDROGEL IMPROVES THE SURVIVAL OF TRANSPLANTED ALLOGENEIC STEM CELLS IN INFARCTED HEART

Bone marrow derived allogeneic mesenchymal stem cells (MSCs) are in clinical trials for myocardial repair after a cardiac injury. However, recent reviews of allogeneic MSCs based clinical trials reported that transplanted cells were not able to survive for long term in the heart. Therefore, strategies to improve survival of transplanted cells would preserve the benefits of allogeneic MSCs therapy for heart repair. Recently, graphene oxide (GO) based biomaterials are being widely investigated for their ability to improve survival of transplanted MSCs in the heart. However, the presence of reactive oxygen functional groups (-OH, -COOH) in the structure of GO increases oxidative stress and activate cell death pathways, which impairs the benefits of GO based biomaterials. Therefore, to improve benefits of GO for stem cell delivery, we synthesized a thermosensitive hydrogel by conjugating GO with chitosan (CS). Our fourier transformed infrared spectrum (FTIR) analysis revealed an interaction between oxygen functional groups of GO and amino (-NH2) groups of chitosan. Our data demonstrate that CS masked the reactive functional groups of GO and prevented GO mediated ROS induction. This novel chitosan-graphene oxide (CS-GO) composite exhibited optimal porosity for cell conjugation and retention. Furthermore, CS-GO biomaterial was cyto-compatible as there was no cytotoxicity caused by CS-GO to MSCs. The CS-GO also prevented hypoxia induced apoptosis of mesenchymal stem cells. We employed this novel biomaterial to deliver allogeneic mesenchymal stem cells to the infarcted heart in a rat model of myocardial infarction. After five weeks of cell transplantation, there was a significant improvement in the survival of implanted MSCs and cardiac function in CS-GO group. Therefore, conjugation of GO with chitosan prevented GO mediated ROS generation and cell death. Also, CS-GO mediated delivery of allogeneic MSCs to infarcted heart improved the survival of transplanted cells and preserved cardiac function.

Rotary jet-spun porous microfibers as scaffolds for stem cells delivery to central nervous system injury

Stem cell transplantation is a promising strategy to treat brain injuries. However, cell-based therapies are limited because poor local cell engraftment. Here, we present a polylactic acid (PLA) scaffold to support mesenchymal stem cells (MSCs) delivery in stroke. We isolated bone marrow MSCs from adult C57/Bl6 mice, cultured them on PLA polymeric rough microfibrous (PRM) scaffolds obtained by rotary jet spinning, and transplanted over the brains of adult C57/Bl6 mice, carrying thermocoagulation-induced cortical stroke. No inflammatory response to PRM was found. MSCs transplantation significantly reduced the area of the lesion and PRM delivery increased MSCs retention at the injury site. In addition, PRM upregulated α6-integrin and CXCL12 production, which may be the cause for greater cell retention at the lesion site and may provide additional benefit to MSCs transplantation procedures. We conclude that PRM scaffolds offer a promising new system to deliver stem cells to injured areas of the brain.

Improved in situ seeding of 3D printed scaffolds using cell-releasing hydrogels

The design of tissue engineered scaffolds based on polymerized high internal phase emulsions (polyHIPEs) has emerged as a promising bone grafting strategy. We previously reported the ability to 3D print emulsion inks to better mimic the structure and mechanical properties of native bone while precisely matching defect geometry. In the current study, redox-initiated hydrogel carriers were investigated for in situ delivery of human mesenchymal stem cells (hMSCs) utilizing the biodegradable macromer, poly(ethylene glycol)-dithiothreitol. Hydrogel carrier properties including network formation time, sol-gel fraction, and swelling ratio were modulated to achieve rapid cure without external stimuli and a target cell-release period of 5–7 days. These in situ carriers enabled improved distribution of hMSCs in 3D printed polyHIPE grafts over standard suspension seeding. Additionally, carrier-loaded polyHIPEs supported sustained cell viability and osteogenic differentiation of hMSCs post-release. In summary, these findings demonstrate the potential of this in situ curing hydrogel carrier to enhance the cell distribution and retention of hMSCs in bone grafts. Although initially focused on improving bone regeneration, the ability to encapsulate cells in a hydrogel carrier without relying on external stimuli that can be attenuated in large grafts or tissues is expected to have a wide range of applications in tissue engineering.

A totally recombinant fibrin matrix for mesenchymal stem cell culture and delivery.

Mesenchymal stem cells (MSCs) have been widely studied for tissue engineering and treating diseases in laboratories, clinical trials, and clinics. Fibrin matrices are often used to culture MSCs or increase the retention of MSCs at the injection site. However, fibrins made with the human plasma derived fibrinogen have high cost and risk of human pathogen transmission. In this article, we studied if fibrin matrices made with recombinant human fibrinogen, recombinant human thrombin, and recombinant human factor XIII could be used to culture and deliver MSCs. We systematically investigated the relationships between the fibrin matrix formulation, its nanostructure, and the behaviors of the cells in the matrix including the cell morphology, viability, and growth. We found that the fibrinogen concentration significantly affected the matrix structure and cell behaviors. We then used an optimized fibrin matrix to deliver human MSCs into mice subcutaneously. We found that the matrix could significantly enhance the retention of MSCs at the injection site. To our best knowledge, this is the first study on using fibrin matrices made with entirely recombinant proteins for culturing and delivering MSCs. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3135-3142, 2018.

A Light-Triggered Mesenchymal Stem Cell Delivery System for Photoacoustic Imaging and Chemo-Photothermal Therapy of Triple Negative Breast Cancer.

Targeted therapy is highly challenging and urgently needed for patients diagnosed with triple negative breast cancer (TNBC). Here, a synergistic treatment platform with plasmonic–magnetic hybrid nanoparticle (lipids, doxorubicin (DOX), gold nanorods, iron oxide nanocluster (LDGI))–loaded mesenchymal stem cells (MSCs) for photoacoustic imaging, targeted photothermal therapy, and chemotherapy for TNBC is developed. LDGI can be efficiently taken up into the stem cells with good biocompatibility to maintain the cellular functions. In addition, CXCR4 on the MSCs is upregulated by iron oxide nanoparticles in the LDGI. Importantly, the drug release and photothermal therapy can be simultaneously achieved upon light irradiation. The released drug can enter the cell nucleus and promote cell apoptosis. Interestingly, light irradiation can control the secretion of cellular microvehicles carrying LDGI for targeted treatment. A remarkable in vitro anticancer effect is observed in MDA‐MB‐231 with near‐infrared laser irradiation. In vivo studies show that the MSCs‐LDGI has the enhanced migration and penetration abilities in the tumor area via both intratumoral and intravenous injection approaches compared with LDGI. Subsequently, MSCs‐LDGI shows the best antitumor efficacy via chemo‐photothermal therapy compared to other treatment groups in the TNBC model of nude mice. Thus, MSCs‐LDGI multifunctional system represents greatly synergistic potential for cancer treatment.

Abstract 331: Conjugation of Graphene Oxide With Chitosan Improves Survival of Transplanted Allogeneic Stem Cells and Preserves Ventricular Function in the Infarcted Heart

Allogeneic mesenchymal stem cells (MSCs) derived from bone marrow are considered to ideal candidate cell type for myocardial repair after a cardiac injury. However, recent reviews of allogeneic MSCs based clinical trials reported that transplanted cells were not able to survive for long term in the heart. Therefore, strategies to improve survival of transplanted cells would preserve the benefits of allogeneic MSCs therapy for heart repair. Recently, graphene oxide (GO) based biomaterials are being widely investigated for their ability to improve survival of transplanted MSCs in the heart. However, the presence of reactive oxygen functional groups (-OH, -COOH) in the structure of GO increases oxidative stress and activate cell death pathways, which impairs the benefits of GO based biomaterials. Therefore, to improve benefits of GO for stem cell delivery, we synthesized a thermosensitive hydrogel by conjugating GO with chitosan (CS). Our fourier transformed infrared spectrum (FTIR) analysis revealed an interaction between oxygen functional groups of GO and amino (-NH2) groups of chitosan. Our data demonstrate that CS masked the reactive functional groups of GO and prevented GO mediated ROS induction. This novel chitosan-graphene oxide (CS-GO) composite exhibited optimal porosity for cell conjugation and retention. Furthermore, CS-GO biomaterial was cyto-compatible as there was no cytotoxicity caused by CS-GO to MSCs. Furthermore, CS-GO also prevented hypoxia induced apoptosis of MSCs. We employed this novel biomaterial to deliver allogeneic MSCs to the infarcted heart in a rat model of myocardial infarction. After 5 weeks of cell transplantation, there was a significant improvement in the survival of implanted MSCs and cardiac function in CS-GO group. Therefore, conjugation of GO with chitosan prevented GO mediated ROS generation and cell death. Also, CS-GO mediated delivery of allogeneic MSCs to infarcted heart improved the survival of transplanted cells and preserved cardiac function.

Image-Guided Resection of Glioblastoma and Intracranial Implantation of Therapeutic Stem Cell-seeded Scaffolds.

Glioblastoma (GBM), the most common and aggressive primary brain cancer, carries a life expectancy of 12-15 months. The short life expectancy is due in part to the inability of the current treatment, consisting of surgical resection followed by radiation and chemotherapy, to eliminate invasive tumor foci. Treatment of these foci may be improved with tumoricidal human mesenchymal stem cells (MSCs). MSCs exhibit potent tumor tropism and can be engineered to express therapeutic proteins that kill tumor cells. Advancements in preclinical models indicate that surgical resection induces premature MSC loss and reduces therapeutic efficacy. Efficacy of MSC treatment can be improved by seeding MSCs on a biodegradable poly(lactic acid) (PLA) scaffold. MSC delivery into the surgical resection cavity on a PLA scaffold restores cell retention, persistence, and tumor killing. To study the effects of MSC-seeded PLA implantation on GBM, an accurate preclinical model is needed. Here we provide a preclinical surgical protocol for image-guided tumor resection of GBM in immune-deficient mice followed by MSC-seeded scaffold implantation. MSCs are engineered with lentiviral constructs to constitutively express and secrete therapeutic TNFα-related apoptosis-inducing ligand (TRAIL) as well as green fluorescent protein (GFP) to allow fluorescent tracking. Similarly, the U87 tumor cells are engineered to express mCherry and firefly luciferase, providing dual fluorescent/luminescent tracking. While currently used for investigating stem cell mediated delivery of therapeutics, this protocol could be modified to investigate the impact of surgical resection on other GBM interventions.

Comparison of Mesenchymal Stem Cell Efficacy in Ischemic Versus Nonischemic Dilated Cardiomyopathy

BackgroundIschemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) differ in histopathology and prognosis. Although transendocardial delivery of mesenchymal stem cells is safe and provides cardiovascular benefits in both, a comparison of mesenchymal stem cell efficacy in ICM versus DCM has not been done.Methods and ResultsWe conducted a subanalysis of 3 single‐center, randomized, and blinded clinical trials: (1) TAC‐HFT (Transendocardial Autologous Mesenchymal Stem Cells and Mononuclear Bone Marrow Cells in Ischemic Heart Failure Trial); (2) POSEIDON (A Phase I/II, Randomized Pilot Study of the Comparative Safety and Efficacy of Transendocardial Injection of Autologous Mesenchymal Stem Cells Versus Allogeneic Mesenchymal Stem Cells in Patients With Chronic Ischemic Left Ventricular Dysfunction Secondary to Myocardial Infarction); and (3) POSEIDON‐DCM (Percutaneous Stem Cell Injection Delivery Effects on Neomyogenesis in Dilated Cardiomyopathy). Baseline and 1‐year cardiac structure and function and quality‐of‐life data were compared in a post hoc pooled analysis including ICM (n=46) and DCM (n=33) patients who received autologous or allogeneic mesenchymal stem cells. Ejection fraction improved in DCM by 7% (within‐group, P=0.002) compared to ICM (1.5%; within‐group, P=0.14; between‐group, P=0.003). Similarly, stroke volume increased in DCM by 10.59 mL (P=0.046) versus ICM (−0.2 mL; P=0.73; between‐group, P=0.02). End‐diastolic volume improved only in ICM (10.6 mL; P=0.04) and end‐systolic volume improved only in DCM (17.8 mL; P=0.049). The sphericity index decreased only in ICM (−0.04; P=0.0002). End‐diastolic mass increased in ICM (23.1 g; P<0.0001) versus DCM (−4.1 g; P=0.34; between‐group, P=0.007). The 6‐minute walk test improved in DCM (31.1 m; P=0.009) and ICM (36.3 m; P=0.006) with no between‐group difference (P=0.79). The New York Heart Association class improved in DCM (P=0.005) and ICM (P=0.02; between‐group P=0.20). The Minnesota Living with Heart Failure Questionnaire improved in DCM (−19.5; P=0.002) and ICM (−6.4; P=0.03; δ between‐group difference P=0.042) patients.ConclusionsMesenchymal stem cell therapy is beneficial in DCM and ICM patients, despite variable effects on cardiac phenotypic outcomes. Whereas cardiac function improved preferentially in DCM patients, ICM patients experienced reverse remodeling. Mesenchymal stem cell therapy enhanced quality of life and functional capacity in both etiologies.Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifiers: TAC‐HFT: NCT00768066, POSEIDON: NCT01087996, POSEIDON‐DCM: NCT01392625.

Renal Intra-Arterial Delivery of MSC to Ischemic Porcine Kidneys

MePEP consortium. Donor organ shortage is one of the main problems in kidney transplantation. The increase in the available donor kidney pool comes with the use of expanded criteria donor organs, leading to a poorer outcome for the grafts and the patients. Therefore, a number of techniques are arising to improve the organ quality, such as machine perfusion in combination with cell therapy. Mesenchymal stem cells (MSC) have tissue regenerative capacities exerted by paracrine secretion of different cytokines and physical interaction with surrounding cells. Porcine MSC from adipose tissue were isolated and grown to carry out the experiments. A model of unilateral ischemia-reperfusion injury by clamping the renal artery for 1 hour was established. 10 million MSC were fluorescently labelled with Qtracker beads and infused directly through the renal artery during 10 minutes. Fluorescent MSC were detected using flow cytometry Before, during and after the infusion, blood samples were taken from the renal vein to assess if MSC were leaving the kidney. After 30 minutes or 8 hours both kidneys were retrieved and biopsies were collected from multiple sites. These biopsies were mechanically disrupted and enzymatically digested to a single cell suspension and analyzed by flow cytometry. Slices from paraffin-embedded biopsies were stained by hematoxylin and eosin and analyzed by light and fluorescence microscopy to identify the exact localization of the administered MSC. Flow cytometric analyses of blood samples allowed us to observe MSC leaving the kidney (up to 2000 MSC/ml blood) during the infusion procedure, after which very low fluorescent cells were detected in renal venous blood (300 MSC/ml). Arterial blood was also analyzed but no MSC was identified. Flow cytometric analysis of dissociated renal cortex and medulla revealed that most MSC were present in renal cortex (8000-20000 MSC/gram of cortex) but a number of individual MSC were detected in the medulla (1000-3000 MSC/gram of medulla). From these MSC inside renal tissue, 80% were alive. Lung tissue was also analyzed and shown to contain a small population of MSC (200-400 MSC/ gram). Microscopy data validated these results. MSC were detected in the renal cortex, mainly inside the glomeruli but individual MSC were found also in tubuli, vessels and medulla.Delivery of MSC through the renal artery can successfully deliver MSC throughout the kidney. MSC were retained particularly in glomeruli for at least 8 hours. We were able to estimate the relative retainment and localization of MSC in the kidney. These studies will pave the way for survival studies in this large animal model aiming for future clinical studies with targeted delivery of MSC in renal disease, eg. in transplantation of high risk donor organs. Lundbeck Foundation under grant application no. R198-2015-184

Aggregate mesenchymal stem cell delivery ameliorates the regenerative niche for muscle repair.

Duchenne muscular dystrophy is a severe muscle wasting disease due to the absence of the dystrophin protein from the muscle cell membrane, which renders the muscle susceptible to continuous damage. In Duchenne muscular dystrophy patients, muscle weakness, together with cycles of degeneration/regeneration and replacement with noncontractile tissue, limit mobility and lifespan. Because the loss of dystrophin results in loss of polarity and a reduction in the number of self-renewing satellite cells, it is postulated that these patients could achieve an improved quality of life if delivered cells could restore satellite cell function. In this study, we used both an established myotoxic injury model in wild-type (WT) mice and mdx mice alone (spontaneous muscle damage). Single (SC) and aggregated (AGG) mesenchymal stem cells (MSCs) were injected into the gastrocnemius muscles 4hr after injury (WT mice). The recovery of peak isometric torque was longitudinally assessed over 5weeks, with earlier takedowns for histological assessment of healing (fibre cross-section area and central nucleation) and MSC retention. AGG-treated WT mice had significantly greater torque recovery at Day 14 than SC or saline-treated mice and a greater CSA at Day 10, compared with SC/saline. AGG-treated mdx mice had a greater peak isometric torque compared with SC/saline. In vitro immunomodulatory factor secretion of AGG-MSCs was higher than SC-MSCs for all tested growth factors with the largest difference observed in hepatocyte growth factor. Future studies are necessary to pair immunomodulatory factor secretion with functional attributes, to better predict the potential therapeutic value of MSC treatment modalities.

Enhanced Homing Technique of Mesenchymal Stem Cells Using Iron Oxide Nanoparticles by Magnetic Attraction in Olfactory-Injured Mouse Models.

Intranasal delivery of mesenchymal stem cells (MSCs) to the olfactory bulb is a promising approach for treating olfactory injury. Additionally, using the homing phenomenon of MSCs may be clinically applicable for developing therapeutic cell carriers. Herein, using superparamagnetic iron oxide nanoparticles (SPIONs) and a permanent magnet, we demonstrated an enhanced homing effect in an olfactory model. Superparamagnetic iron oxide nanoparticles with rhodamine B (IRBs) had a diameter of 5.22 ± 0.9 nm and ζ-potential of +15.2 ± 0.3 mV. IRB concentration of 15 µg/mL was injected with SPIONs into MSCs, as cell viability significantly decreased when 20 μg/mL was used (p ≤ 0.005) compared to in controls. The cells exhibited magnetic attraction in vitro. SPIONs also stimulated CXCR4 (C-X-C chemokine receptor type 4) expression and CXCR4-SDF-1 (Stromal cell-derived factor 1) signaling in MSCs. After injecting magnetized MSCs, these cells were detected in the damaged olfactory bulb one week after injury on one side, and there was a significant increase compared to when non-magnetized MSCs were injected. Our results suggest that SPIONs-labeled MSCs migrated to injured olfactory tissue through guidance with a permanent magnet, resulting in better homing effects of MSCs in vivo, and that iron oxide nanoparticles can be used for internalization, various biological applications, and regenerative studies.

A Systematic Review and Meta-analysis of Mesenchymal Stem Cell Injections for the Treatment of Perianal Crohn’s Disease: Progress Made and Future Directions

There has been a surge in clinical trials studying the safety and efficacy of mesenchymal stem cells for the treatment of perianal Crohn's disease. The purpose of this work was to systematically review the literature to determine safety and efficacy of mesenchymal stem cells for the treatment of refractory perianal Crohn's disease. Sources included PubMed, Cochrane Library Central Register of Controlled Trials, and Embase. Studies that reported safety and/or efficacy of mesenchymal stem cells for the treatment of perianal Crohn's disease were included. Two independent assessors reviewed eligible articles. The study intervention was delivery of mesenchymal stem cells to treat perianal Crohn's disease. Safety and efficacy of mesenchymal stem cells used to treat perianal Crohn's disease were measured. Eleven studies met the inclusion criteria and were included in the systematic review. Three trials with a comparison arm were included in the meta-analysis. There were no significant increases in adverse events (OR = 1.07 (95% CI, 0.61-1.89); p = 0.81) or serious adverse events (OR = 0.53 (95% CI, 0.28-0.98); p = 0.04) in patients treated with mesenchymal stem cells. Mesenchymal stem cells were associated with improved healing as compared with control subjects at primary end points of 6 to 24 weeks (OR = 3.06 (95% CI, 1.05-8.90); p = 0.04) and 24 to 52 weeks (OR = 2.37 (95% CI, 0.90-6.25); p = 0.08). The study was limited by its multiple centers and heterogeneity in the study inclusion criteria, mesenchymal stem cell origin, dose and frequency of delivery, use of scaffolding, and definition and time point of fistula healing. Although there have been only 3 trials conducted with control arms, existing data demonstrate improved efficacy and no increase in adverse or serious adverse events with mesenchymal stem cells as compared with control subjects for the treatment of perianal Crohn's disease.

A MMP7-sensitive photoclickable biomimetic hydrogel for MSC encapsulation towards engineering human cartilage.

Cartilage tissue engineering strategies that use in situ forming degradable hydrogels for mesenchymal stem cell (MSC) delivery are promising for treating chondral defects. Hydrogels that recapitulate aspects of the native tissue have the potential to encourage chondrogenesis, permit cellular mediated degradation, and facilitate tissue growth. This study investigated photoclickable poly(ethylene glycol) hydrogels, which were tailored to mimic the cartilage microenvironment by incorporating extracellular matrix analogs, chondroitin sulfate and RGD, and crosslinks sensitive to matrix metalloproteinase 7 (MMP7). Human MSCs were encapsulated in the hydrogel, cultured up to nine weeks, and assessed by mRNA expression, protein production and biochemical analysis. Chondrogenic genes, SOX9, ACAN, and COL2A1, significantly increased with culture time, and the ratios of COL2A1:COL10A1 and SOX9:RUNX2 reached values of ∼20-100 by week 6. The encapsulated MSCs degraded the hydrogel, which was nearly undetectable by week 9. There was substantial deposition of aggrecan and collagen II, which correlated with degradation of the hydrogel. Minimal collagen X was detectable, but collagen I was prevalent. After week1, extracellular matrix elaboration was accompanied by a ∼twofold increase in compressive modulus with culture time. The MMP7-sensitive cartilage mimetic hydrogel supported MSC chondrogenesis and promoted macroscopic neocartilaginous matrix elaboration representative of fibrocartilage. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2344-2355, 2018.

Enzymatically crosslinked and mechanically tunable silk fibroin/pullulan hydrogels for mesenchymal stem cells delivery

Hydrogels with good biocompatibility, proper degradation rates, and tissue-matched elasticity are widely used in tissue engineering, regenerative medicine, and drug delivery. In this study, enzymatically crosslinked biocompatible hydrogels were successfully developed using silk fibroin (SF) and pullulan (PL) under physiological conditions in the presence of both horseradish peroxidase and hydrogen peroxide. A series of properties of the hydrogels including gelation time, equilibrium swelling, enzyme degradation, morphology, rheological property, and compression modulus of SF/PL hydrogels were studied by varying the concentration of PL. The results showed that the SF/PL hydrogels had applicable gel-forming rate (ranging from 12 to 60 min), tunable compressive strength (ranging from 7 to 71 kPa) and shear mechanical properties (ranging from 200 to 1470 Pa). The properties of the SF/PL hydrogels were easily modulated by changing the concentration of PL. The compressive modulus of the SF + 20%PL hydrogels was 71.4 ± 9.3 kPa, which was in the range of that of musculoskeletal system. In addition, the rabbit bone marrow-derived mesenchymal stem cells were encapsulated in SF/PL hydrogels for 7 days, and cell viability and morphology were observed. Live/dead staining assay demonstrated that the hydrogel system possessed good cytocompatibility. These features support that SF/PL hydrogels have a potential as cell delivery scaffold in musculoskeletal tissue engineering.

Simultaneous Delivery of Wharton's Jelly Mesenchymal Stem Cells and Insulin-Like Growth Factor-1 in Acute Myocardial Infarction.

Wharton's jelly mesenchymal stem cells (HWJMSCs) hold promise for myocardial regeneration, but optimal treatment regimen (preferably with a growth factor) is required to maximize functional benefits. The aim of this study was to explore the cardioprotective and angiogenesis effects of HWJMSCs combined with insulin-like growth factor-1 (IGF-1) in the treatment of acute myocardial infarction. The hydrogel consisted of Polyethylene glycol (PEG) and hyaluronic acid was prepared and characterized with regards to rheology, morphology, swelling, degradation, and release behaviors. To examine in-vivo effects, the hydrogels containing HWJMSCs either alone (Cells/hydrogel group) or with IGF-1 (Cells/hydrogel/IGF-1 group) were intra-myocardially injected into a rabbit myocardial infarction model. In-vivo efficacy was evaluated histological, immunohistochemical, echocardiography, scanning electron microscopy, and SPECT analyses. Eight weeks after infusion, the Cells/hydrogel and Cells/hydrogel/IGF-1 groups exhibited significantly increased left ventricular ejection fraction by echocardiography. Percent of ejection fraction was respectively 18.5% and 40% greater than control (P < 0.01). Vascular density (CD31 positive cells) of both treatment groups were more than the control group and this superiority was more remarkable in Cells/hydrogel/IGF-1 group. Cells/hydrogel/IGF-1 group showed the least defect size in SPECT analysis. Combinatory therapy with HWJMSCs and IGF-1 may additionally improve cardiac function and promote angiogenesis.

Interaction between hypothermia and delayed mesenchymal stem cell therapy in neonatal hypoxic-ischemic brain injury

Acute hypothermia treatment (HT) is the only clinically established intervention following neonatal hypoxic-ischemic brain injury. However, almost half of all cooled infants still die or suffer from long-lasting neurological impairments. Regenerative therapies, such as mesenchymal stem cells (MSC) appear promising as adjuvant therapy. In the present study, we hypothesized that HT combined with delayed MSC therapy results in augmented protection, improving long-term neurological outcome. Postnatal day 9 (P9) C57BL/6 mice were exposed to hypoxia–ischemia followed by 4 h HT. Murine bone marrow-derived MSC (1 × 106 cells/animal) were administered intranasally at P12. Cytokine and growth factor levels were assessed by ELISA and Luminex® multiplex assay 24 h following MSC delivery. One week after HI, tissue injury and neuroinflammatory responses were determined by immunohistochemistry and western blot. Long-term motor-cognitive outcome was assessed 5 weeks post injury. MSC responses to the brains’ environment were evaluated by gene expression analysis in MSC, co-cultured with brain homogenates isolated at P12. Both, MSC and HT improved motor deficits, while cognitive function could only be restored by MSC. Compared to each single therapy, combined treatment led to increased long-lasting motor-cognitive deficits and exacerbated brain injury, accompanied by enhanced endothelial activation and peripheral immune cell infiltration. MSC co-cultured with brain extracts of HT-treated animals revealed increased pro-inflammatory cytokine and decreased growth factor expression. In vivo protein analysis showed higher pro-inflammatory cytokine levels after combined treatment compared to single therapy. Furthermore, HI-induced increase in growth factors was normalized to control levels by HT and MSC single therapy, while the combination induced a further decline below control levels. Our results suggest that alteration of the brains’ microenvironment by acute HT modulates MSC function resulting in a pro-inflammatory environment combined with alteration of the homeostatic growth factor milieu in the neonatal hypoxic-ischemic brain. This study delineates potential unexpected side effects of cell-based therapies as add-on therapy for acute hypothermia treatment.

The effects of bi-functional anti-adhesion scaffolds on flexor tendon healing in a rabbit model.

Progressive tendon adhesion is a major challenge in flexor tendon repair. The authors developed a bifunctional anti-adhesion scaffold and hypothesized that its application would reduce adhesion formation and deliver mesenchymal stem cells (MSCs) to enhance tendon healing. The scaffold was fabricated by an electrospinning machine before surface modification. The flexor tendons of 29 New Zealand rabbits underwent surgical repair and randomized to control, scaffold and scaffold loaded with MSC group. At 3 and 8 weeks post-surgery, range of motion (ROM), biomechanical properties, and histology were examined. There was no significant increase in ROM and biomechanical properties between the three groups. The histology showed successful delivery of MSCs but no significant difference in nuclear morphometry. This barrier delivers and retains MSCs within the tendon repair site. However, its sheet form and wrapping around the repair site may not be optimal for tendon healing. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2605-2614, 2018.