Encapsulated Stem Cells Research Articles

Optimization of agarose–alginate hydrogel bead components for encapsulation and transportation of stem cells

Hydrogels have potential uses in various biological applications because of their unique characteristics. Fine-tuning of agarose–alginate (Ag–Al) hydrogel components improves the mechanical characteristics of the final construct for cell encapsulation and transportation. Formulation of suitable dissolving agents may enable the release of encapsulated cells for further applications in laboratory or clinical settings. ObjectivesThis study aimed at optimizing the composition of Ag–Al hydrogel beads and their dissolving agents for potential use in the transportation of stem cells. MethodsVarious agarose, alginate, and CaCl2 concentrations were tested to construct hydrogel beads. The degradation rate and swelling ratio of each hydrogel sample were recorded. The optimized Ag–Al hydrogels were used for encapsulation of stem cells from human exfoliated deciduous teeth (SHED). Optimization of dissolving agents was performed and tested with the hydrogel-encapsulated cells. Data were statistically analyzed in SPSS. ResultsThe selected concentration of Ag–Al hydrogels components was successfully demonstrated to encapsulate SHED, which remained viable until day 10. An average of 2 min was required for degradation of the hydrogel with encapsulated SHED by a dissolving agent consisting of 100 mM sodium citrate and 100 mM EDTA. The cell viability of SHED released after day 10 of encapsulation was 29.1%. ConclusionAlteration of Ag-Al components has considerable influence on the mechanical properties of the constructed hydrogel. The feasibility of performing the optimized cell encapsulation protocol, as well as the dissolving step, may provide a useful guide for the transportation of viable cells between countries, for medical research.

Material Properties and Cell Compatibility of Photo-Crosslinked Sericin Urethane Methacryloyl Hydrogel.

There is a need to develop novel cytocompatible hydrogels for cell encapsulation and delivery in regenerative medicine. The objective of this work was to synthesize isocyanato ethyl methacryloyl-functionalized sericin and determine its material properties as a natural hydrogel for the encapsulation and delivery of human mesenchymal stem cells (MSCs) in regenerative medicine. Sericin extracted from silk cocoons was reacted with 2-isocyanatoethyl methacrylate (IEM) or methacrylic anhydride (MA) to produce sericin urethane methacryloyl (SerAte-UM) or sericin methacryloyl (SerAte-M, control) biopolymers, respectively. The hydrogels produced by photo-crosslinking of the biopolymers in an aqueous solution were characterized with respect to gelation kinetics, microstructure, compressive modulus, water content, degradation, permeability, and viability of encapsulated cells. The secondary structure of citric acid-extracted sericin was not affected by functionalization with IEM or MA. SerAte-UM hydrogel was slightly more hydrophilic than SerAte-M. The gelation time of SerAte-UM hydrogel decreased with an increasing degree of modification. The photo-polymerized SerAte-UM hydrogel had a highly porous, fibrous, honeycomb microstructure with an average pore size in the 40–50 µm range. The compressive modulus, swelling ratio, and permeability of SerAte-UM hydrogel depended on the degree of modification of sericin, and the mass loss after 21 days of incubation in aqueous solution was <25%. Both SerAte-UM and SerAte-M hydrogels supported viability and growth in encapsulated MSCs. The SerAte-UM hydrogel, with its higher hydrophilicity compared to SerAte-M, is promising as a matrix for encapsulation and delivery of stem cells in tissue engineering.

Engineering Hyaluronic Acid for the Development of New Treatment Strategies for Osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease that is characterized by inflammation of the joints, degradation of cartilage, and the remodeling of other joint tissues. Due to the absence of disease-modifying drugs for OA, current clinical treatment options are often only effective at slowing down disease progression and focus mainly on pain management. The field of tissue engineering has therefore been focusing on developing strategies that could be used not only to alleviate symptoms of OA but also to regenerate the damaged tissue. Hyaluronic acid (HA), an integral component of both the synovial fluid and articular cartilage, has gained widespread usage in developing hydrogels that deliver cells and biomolecules to the OA joint thanks to its biocompatibility and ability to support cell growth and the chondrogenic differentiation of encapsulated stem cells, providing binding sites for growth factors. Tissue-engineering strategies have further attempted to improve the role of HA as an OA therapeutic by developing diverse modified HA delivery platforms for enhanced joint retention and controlled drug release. This review summarizes recent advances in developing HA-based hydrogels for OA treatment and provides additional insights into how HA-based therapeutics could be further improved to maximize their potential as a viable treatment option for OA.

Vascular Cell Adhesion Molecule 1-Mediated Targeting of Human Hematopoietic Stem Cells to Bone Marrow Is Effective in Conferring Regeneration and Survival in Lethally Irradiated Mice

Bone marrow (BM) transplantation has been used to treat malignant and nonmalignant BM-related disorders. Although an effective strategy, the procedure is associated with numerous complications, including graft rejection and nonspecific stem cell distribution. Avoidance of immune graft rejection has downsized the quantity of available stem cells, whereas nonspecific distribution necessitates the infusion of increased stem cell doses. A dual-purpose approach is needed to reduce the stem cell dose for transplantation. This used cell encapsulation and BM targeting to increase the quantity of transplanted stem cells reaching the BM. Cells were encapsulated with different biomaterials-chitosan (CS), polyallylamine hydrochloride (PAH), polystyrene sulfonate (PSS), and liposomes-and assessed for interaction with immune system components. The biomaterials were conjugated with vascular cell adhesion molecule 1 (VCAM1), a peptide that binds to BM-specific cell surface molecule, and evaluated for a successful transplantation. Encapsulated cells showed reduced interaction with antibody and cytokine without adverse effects on viability. Constitutive expression of VCAM1 was found to be specific on human bone marrow endothelial cells and was used for targeting by conjugating VCAM1-binding peptide to encapsulated cells. Peptide-conjugated-encapsulated stem cell formulations transplanted in irradiated mice with or without treatment with radioprotectant amifostine showed an increased percentage of cells reaching bone marrow. Post-transplantation survival along with blood count of neutrophils, platelets, and leukocytes was also enhanced for VCAM1-binding peptide-conjugated formulations with 100% survival demonstrated by peptide-conjugated CS/PSS/CS encapsulation formulation in irradiated mice for 4 weeks. Encapsulated cells retained their viability with increased shielding to the immune system, ensuring that graft rejection can be avoided. Transplanted encapsulated stem cells were distributed in a higher percentage to BM when conjugated to VCAM1-binding peptide, which could enable the use of lower stem cell doses. The peptide-conjugated CS/PSS/CS encapsulation system conferred 100% survival in irradiated mice, with increased regeneration demonstrating the ability to treat radiation-exposed victims.

Human Umbilical Cord Mesenchymal Stem Cells Encapsulated with Pluronic F-127 Enhance the Regeneration and Angiogenesis of Thin Endometrium in Rat via Local IL-1β Stimulation.

Thin endometrium (< 7 mm) could cause low clinical pregnancy, reduced live birth, increased spontaneous abortion, and decreased birth weight. However, the treatments for thin endometrium have not been well developed. In this study, we aim to determine the role of Pluronic F-127 (PF-127) encapsulation of human umbilical cord mesenchymal stem cells (hUC-MSCs) in the regeneration of thin endometrium and its underlying mechanism. Thin endometrium rat model was created by infusion of 95% ethanol. Thin endometrium modeled rat uterus were treated with saline, hUC-MSCs, PF-127, or hUC-MSCs plus PF-127 separately. Regenerated rat uterus was measured for gene expression levels of angiogenesis factors and histological morphology. Angiogenesis capacity of interleukin-1 beta (IL-1β)-primed hUC-MSCs was monitored via quantitative polymerase chain reaction (q-PCR), Luminex assay, and tube formation assay. Decreased endometrium thickness and gland number and increased inflammatory factor IL-1β were achieved in the thin endometrium rat model. Embedding of hUC-MSCs with PF-127 could prolong the hUC-MSCs retaining, which could further enhance endometrium thickness and gland number in the thin endometrium rat model via increasing angiogenesis capacity. Conditional medium derived from IL-1β-primed hUC-MSCs increased the concentration of angiogenesis factors (basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGF), and hepatocyte growth factor (HGF)). Improvement in the thickness, number of glands, and newly generated blood vessels could be achieved by uterus endometrium treatment with PF-127 and hUC-MSCs transplantation. Local IL-1β stimulation-primed hUC-MSCs promoted the release of angiogenesis factors and may play a vital role on thin endometrium regeneration.

Hydrogen‐Bonded Organic Framework (HOF)‐Based Single‐Neural Stem Cell Encapsulation and Transplantation to Remodel Impaired Neural Networks

AbstractHerein we present a new way to encapsulate neural stem cells (NSCs) by using hydrogen‐bonded organic frameworks (HOFs) to overcome the common causes of low therapeutic efficacy during NSC transplantation: 1) loss of fundamental stem cell properties, “stemness”, before transplantation, 2) cytomembrane damage during transplantation, and 3) apoptosis due to oxidative stress after transplantation. Porous carbon nanospheres (PCNs) are doped into the HOF shell during the process of mineralization to endow the cellular exoskeletons with hierarchical hydrogen bonds, and the ability to resist oxidative stress due to the catalase and superoxide dismutase‐like activities of PCN. Under NIR‐II irradiation, thermal‐responsive hydrogen bonds dissociate to release NSCs. Stereotactic transplanting encapsulated NSC into the brain of an Alzheimer's disease (AD) mouse model further verifies that our design can enhance NSC viability, promote neurogenesis, and ameliorate cognitive impairment. As the first example of using HOFs to encapsulate NSCs, this work may inspire the design of HOF‐based exoskeletons to ameliorate neurogenesis and cognitive behavioral symptoms associated with AD.

Hydrogen-Bonded Organic Framework (HOF)-Based Single-Neural Stem Cell Encapsulation and Transplantation to Remodel Impaired Neural Networks.

Herein we present a new way to encapsulate neural stem cells (NSCs) by using hydrogen-bonded organic frameworks (HOFs) to overcome the common causes of low therapeutic efficacy during NSC transplantation: 1) loss of fundamental stem cell properties, "stemness", before transplantation, 2) cytomembrane damage during transplantation, and 3) apoptosis due to oxidative stress after transplantation. Porous carbon nanospheres (PCNs) are doped into the HOF shell during the process of mineralization to endow the cellular exoskeletons with hierarchical hydrogen bonds, and the ability to resist oxidative stress due to the catalase and superoxide dismutase-like activities of PCN. Under NIR-II irradiation, thermal-responsive hydrogen bonds dissociate to release NSCs. Stereotactic transplanting encapsulated NSC into the brain of an Alzheimer's disease (AD) mouse model further verifies that our design can enhance NSC viability, promote neurogenesis, and ameliorate cognitive impairment. As the first example of using HOFs to encapsulate NSCs, this work may inspire the design of HOF-based exoskeletons to ameliorate neurogenesis and cognitive behavioral symptoms associated with AD.

Electrosprayed Regeneration‐Enhancer‐Element Microspheres Power Osteogenesis and Angiogenesis Coupling

Electrosprayed microspheres for bone regeneration are conventionally restricted by the lack of osteogenic modulation for both encapsulated stem cells and surrounding cells at the defect site. Here, sodium alginate microspheres encapsulating L-arginine doped hydroxyapatite nanoparticles (Arg/HA NPs) and bone mesenchymal stem cells (BMSCs) as regeneration-enhancer-element reservoirs (Arg/HA-SA@BMSC) for bone healing are electrosprayed. The Arg/HA NPs serve as a container of L-arginine and Ca2+ and the BMSCs inside the microspheres metabolize the released L-arginine into bioactive gas nitric oxide (NO) in the presence of Ca2+ to activate the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway. Meanwhile, the generated NO diffuses out of the microspheres together with the Ca2+ and L-arginine as exterior enhancers to promote the osteogenesis-angiogenesis coupling of surrounding BMSCs and endothelial cells (ECs) at the bone defect site, generating an internal/external modulation loop between the encapsulated cells and surrounding native cells. It is demonstrated that such regeneration-enhancer-element reservoirs could effectively increase the bone tissue formation and neovasculature using rat calvarial defect models. It is envisioned that the microsphere system could streamline vascularized bone regeneration therapy as a high throughput, minimally invasive yet highly effective strategy to accelerate bone healing.

Mineralized collagen as a bioactive ink to support encapsulation of human adipose stem cells: A step towards the future of bone regeneration

Bioprinting – printing with incorporated living cells – has earned special attention on tissue engineering approaches, aiming to closer reproduce the 3D microenvironment of the target tissue. However, it raises extra complexity related to the need to use cell-friendly printing conditions that still comply with material printing fidelity. Inspired by the composite nano structural organization of mineralized tissues, this work reports the efficiency of the chemical approach followed to in situ mineralize blue shark skin collagen, at a nano scale level, to ultimately produce stable inks. The influence of initial cellular density was evaluated by assessing three different concentrations (2.5, 5 and 7.5 × 106 cells·ml−1) of human adipose stem cells (hASC), with the higher density of encapsulated cells presenting improved viability in a long culture term. Immunodetection of osteogenic-related markers, like RUNX2 and osteopontin, 21 days after cell culture in basal conditions confirmed the potential of the ink to be applied for osteogenic purposes, which may be associated with the success of the cell-to-ink interaction and the Ca2+ ions released from the co-precipitated hydroxyapatite. A combination of mineralized shark collagen, alginate and hASC is thus proposed as a bioactive bioink with potential properties for regeneration of bone tissue.

Effect of Alginate Microbead Encapsulation of Placental Mesenchymal Stem Cells on Their Immunomodulatory Function.

In this research we have used different cytokines and progesterone to enhance the immunomodulatory capacity of placental-derived stem cells (PLSCs) prior to their encapsulation. We assessed the effect of microencapsulation of the cells without (control) or after 3-day treatment with interferon gamma (INFγ), interleukin10 (IL-10), or progesterone (P4). Treated PLSCs demonstrated strong immunosuppressive effects on phytohemagglutinin (PHA)-activated peripheral blood mononuclear cells (PBMNCs). INFγ treatment resulted in the strongest immune inhibition among the treated groups. The treatments enhanced soluble human leukocyte antigen (sHLAG) secretion compared to control. The IL-10-treated group showed the highest effect on HLAG secretion compared to other groups. Alginate encapsulation of PLSCs did not affect cell viability, or sHLAG secretion. Also, after treatment the encapsulated PLSCs inhibited PHA-activated PBMNCs in the same manner as unencapsulated cells. We studied two groups of encapsulated PLSCs, one without perm-selective poly-L-ornithine (PLO)-coating and the other with PLO-coating, and measured levels of sHLAG secreted. We found no difference in sHLAG secretion between both groups. In summary, our data show that immunomodulatory function of the PLSC is not affected by encapsulation. These findings provide good promise for potential use of encapsulated PLSCs for immunomodulation treatment of disease by stem cell therapy.

The Effects of Irradiation Time on Gelatin Methacrylate Hydrogels Used for Bone Tissue Engineering

Gelatin methacrylate (GelMA) hydrogels are a promising material for use in a variety of tissue engineering applications. Herein, we focused on identifying the optimal irradiation time necessary to photopolymerize GelMA hydrogels with visible blue light in a manner that did not adversely impact the biophysical properties of these cell-containing gels. We assessed the toxic effects of different irradiation times (3, 5, 10, 20 and 40 seconds) on BMMSCs encapsulated in a GelMA hydrogel using lithium phenyl-2,4,6 trimethylbenzoylphosphinate (LAP) as a photoinitiator. Both CCK-8 assays and Live-Dead staining were used to measure BMMSCs viability. We observed increasing compression strength as a function of increased irradiation time, although this corresponded to a reduction in swelling ratio and pore sizes. We ultimately found that when using LAP as a photoinitiator, the optimal irradiation time was 5–10 seconds, which was suitable for bone tissue engineering application. Ultimately we determined that a 5 second irradiation time was optimal for studies of encapsulated stem cells.

Biomass Microcapsules with Stem Cell Encapsulation for Bone Repair

HighlightsA novel stem cell delivery core-shell biomass microcapsule was generated by an all-aqueous phase microfluidic electrospray technique.Microcapsule with a certain mechanical strength and porous structure is beneficial for substances exchange between cells and the external environment, together with avoiding cell damage during treatment.Core-shell microcapsule provided a favorable cell growth microenvironment, which mimics a physicochemical microenvironment and protects the cells from the immune attack from body.

Microfluidic-templating alginate microgels crosslinked by different metal ions as engineered microenvironment to regulate stem cell behavior for osteogenesis

Cell microenvironment is a collection of dynamic biochemical and biophysical cues which functions as the key factor in determining cell behavior. Encapsulating single cell into micrometer-scale hydrogels which mimics the cell microenvironment can be used for single cell analysis, cell therapies, and tissue engineering. Here, we developed a microfluidics-based platform to engineer the niche environment at single cell level using alginate microgels crosslinked by different metal ions to regulate stem cell behavior for bone regeneration. Specifically, we revealed that Ca2+ in the engineered microenvironment promoted osteogenic differentiation of encapsulated stem cells and substantially accelerated the matrix mineralization compared to Sr2+in vitro. However, the superior osteoinductive capacity of Ca2+ compared with Sr2+ led to comparable bone healing in a rat bone defect model. This attributed to Sr2+ in microgels to inhibit the osteoclast activity and bone resorption after implantation. In summary, the present study demonstrates metal ions as a critical factor in the environmental cues to affect cell behavior and influence the efficacy of stem cell-based therapy in tissue regeneration, and provides new insights to engineer an expecting microenvironment for regenerative medicine.

Therapeutic potentials of human microfluidic encapsulated conjunctival mesenchymal stem cells on the rat model of Parkinson's disease

Background and aimParkinson's disease (PD) is a progressive neurodegenerative disorder caused by the destruction of the dopaminergic neurons in the nigrostriatal pathway, leading to motor-behavioral complications. Cell therapy has been proposed as a promising approach for PD treatment using various cellular sources. Despite a few disadvantages mesenchymal stem cells (MSCs) represent, they have more auspicious effects for PD cell therapy. The present study aimed to evaluate a new source of MSCs isolated from human Conjunctiva (CJ-MSCs) impact on PD complications for the first time. Materials and methodsParkinson's was induced by stereotactic injection of 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle (MFB). An apomorphine-induced rotation test was used to confirm the model establishment. After PD model confirmation, green fluorescent protein (GFP) labeled CJ-MSCs and induced CJ-MSCs (microfluidic encapsulated and non-capsulated) were transplanted into the rats' right striatum. Then Rotation, Rotarod, and Open-field tests were performed to evaluate the behavioral assessment. Additionally, the immunohistochemistry technique was used for identifying tyrosine hydroxylase (TH). ResultsAccording to the obtained data, the cell transplantation caused a reduction in the rats' rotation number and improved locomotion compared to the control group. The previous results were also more pronounced in induced and microfluidic encapsulated cells compared to other cells. Rats recipient CJ-MSCs also have represented more TH-expressed GFP-labeled cell numbers in the striatum than the control group. ConclusionIt can be concluded that CJ-MSCs therapy can have protective effects against PD complications and nerve induction of cells due to their ability to express dopamine. On the other hand, CJ-MSCs microencapsulating leads to enhance even more protective effect of CJ-MSCs. However, confirmation of this hypothesis requires further studies and investigation of these cells' possible mechanisms of action.

Recent Advances in Cardiac Tissue Engineering for the Management of Myocardium Infarction.

Myocardium Infarction (MI) is one of the foremost cardiovascular diseases (CVDs) causing death worldwide, and its case numbers are expected to continuously increase in the coming years. Pharmacological interventions have not been at the forefront in ameliorating MI-related morbidity and mortality. Stem cell-based tissue engineering approaches have been extensively explored for their regenerative potential in the infarcted myocardium. Recent studies on microfluidic devices employing stem cells under laboratory set-up have revealed meticulous events pertaining to the pathophysiology of MI occurring at the infarcted site. This discovery also underpins the appropriate conditions in the niche for differentiating stem cells into mature cardiomyocyte-like cells and leads to engineering of the scaffold via mimicking of native cardiac physiological conditions. However, the mode of stem cell-loaded engineered scaffolds delivered to the site of infarction is still a challenging mission, and yet to be translated to the clinical setting. In this review, we have elucidated the various strategies developed using a hydrogel-based system both as encapsulated stem cells and as biocompatible patches loaded with cells and applied at the site of infarction.

Reversible dynamic mechanics of hydrogels for regulation of cellular behavior

The mechanical properties of the native extracellular matrix play a key role in regulating cell behavior during developmental, healing and homeostatic processes. Since these properties change over time, it may be valuable to have the capacity to dynamically vary the mechanical properties of engineered hydrogels used in tissue engineering strategies to better mimic the dynamic mechanical behavior of native extracellular matrix. However, in situ repeatedly reversible dynamic tuning of hydrogel mechanics is still limited. In this study, we have engineered a hydrogel system with reversible dynamic mechanics using a dual-crosslinkable alginate hydrogel. The effect of reversible mechanical signals on encapsulated stem cells in dynamically tunable hydrogels has been demonstrated. In situ stiffening of hydrogels decreases cell spreading and proliferation, and subsequent softening of hydrogels gives way to an increase in cell spreading and proliferation. The hydrogel stiffening and softening, and resulting cellular responses are repeatedly reversible. This hydrogel system provides a promising platform for investigating the effect of repeatedly reversible changes in extracellular matrix mechanics on cell behaviors. Statement of significanceSince the mechanical properties of native extracellular matrix (ECM) change over time during development, healing and homeostatic processes, it may be valuable to have the capacity to dynamically control the mechanics of biomaterials used in tissue engineering and regenerative medicine applications to better mimic this behavior. Unlike previously reported biomaterials whose mechanical properties can be changed by the user only a limited number of times, this system provides the capacity to induce unlimited alterations to the mechanical properties of an engineered ECM for 3D cell culture. This study presents a strategy for on-demand dynamic and reversible control of materials’ mechanics by single and dual-crosslinking mechanisms using oxidized and methacrylated alginates. By demonstrating direct changes in encapsulated human mesenchymal stem cell morphology, proliferation and chondrogenic differentiation in response to multiple different dynamic changes in hydrogel mechanics, we have established a repeatedly reversible 3D cellular mechanosensing system. This system provides a powerful platform tool with a wide range of stiffness tunability to investigate the role of dynamic mechanics on cellular mechanosensing and behavioral responses.

Methacrylated Gellan Gum/Poly-l-lysine Polyelectrolyte Complex Beads for Cell-Based Therapies.

Cell encapsulation strategies using hydrogel beads have been considered as an alternative to immunosuppression in cell-based therapies. They rely on layer-by-layer (LbL) deposition of polymers to tune beads' permeability, creating a physical barrier to the host immune system. However, the LbL approach can also create diffusion barriers, hampering the flow of essential nutrients and therapeutic cell products. In this work, the polyelectrolyte complex (PEC) methodology was used to circumvent the drawbacks of the LbL strategy by inducing hydrogel bead formation through the interaction of anionic methacrylated gellan gum (GG-MA) with cationic poly-l-lysine (PLL). The interfacial complexation between both polymers resulted in beads with a cell-friendly GG-MA hydrogel core surrounded by a PEC semipermeable membrane. The beads showed great in vitro stability over time, a semi-permeable behavior, and supported human adipose-derived stem cell encapsulation. Additionally, and regarding immune recognition, the in vitro and in vivo studies pointed out that the hydrogel beads behave as an immunocompatible system. Overall, the engineered beads showed great potential for hydrogel-mediated cell therapies, when immunoprotection is required, as when treating different metabolic disorders.

Abstract P393: Fabrication Of Immunomodulatory Hydrogels For Cardiac Repair After Acute Myocardial Infaction

Introduction: The balance of pro- and anti-inflammatory processes is tightly linked to left ventricular remodeling after myocardial infarction. Immune activation also plays a key role in rejection of transplanted allogeneic stem cells. In this study, we present the design, fabrication and characterization of immunomodulatory chitosan-based hydrogels for cardiac repair after myocardial infarction. Methods: Chitosan hydrogels conjugated with small immunomodulatory molecules were synthesized through a thermogelation process. Resultant hydrogels were characterized using scanning electron microscopy and Fourier-transformed infrared spectroscopy. Human mesenchymal stem cells were encapsulated into the hydrogels and biocompatibility was assessed after one week using fluorescence microscopy and a colorimetric assay. Immunomodulatory activity was assessed after co-culture with human T-lymphocytes using flow cytometry for CD4+IFN-γ+ pro-inflammatory and CD4+CD25+FoxP3+ regulatory T-lymphocytes. Results: Small immunomodulatory molecules were successfully integrated into chitosan hydrogels. Physico-chemical characterization revealed no significant changes to the 3D structure and porosity of hydrogels. The addition of 10μM atorvastatin or 10μM rosuvastatin did not result in significant cytotoxicity to encapsulated mesenchymal stem cells at 3 or 7 days. Addition of statins resulted in marked suppression of CD4+ T-lymphocyte proliferation (Control 25.1 Fold, Atorvastatin 1.0 Fold, Rosuvastatin 2.3 Fold, p&lt;0.001) and activation (CD4+IFN-γ+ Population: Control 87.1%, Rosuvastatin 23.7%, p&lt;0.001) after stimulation. No differences were seen in percentages of CD4+CD25+FoxP3+ regulatory T-lymphocytes (Control 5.5%, Rosuvastatin 5.7%, ns). Conclusion: A biocompatible immunomodulatory hydrogel was created through integration of atorvastatin and rosuvastatin into a chitosan hydrogel. Experiments are currently underway in vivo to examine its usefulness for stem cell delivery and reducing adverse left ventricular remodeling after myocardial infarction.

Bioprinting of a Blue Light-Cross-Linked Biodegradable Hydrogel Encapsulating Amniotic Mesenchymal Stem Cells for Intrauterine Adhesion Prevention.

Intrauterine adhesion (IUA) is a common and prevailing complication after uterine surgery, which can lead to clinical symptoms such as a low menstrual volume, amenorrhea, periodic lower abdominal pain, infertility, and so on. Placing a three-dimensional printing hydrogel between the injured site and the adjacent tissue is considered to be a physical barrier to prevent adhesion, which can isolate the damaged area during the healing process. In this work, a tissue hydrogel with various proportions of a methacrylated gelatin (GelMA) and methacrylated collagen (ColMA) composite hydrogel loaded with amniotic mesenchymal stem cells (AMSCs) was constructed by using three-dimensional biological printing technology. Compared with the single GelMA hydrogel, the composite antiadhesion hydrogel (GelMA/ColMA) showed an appropriate swelling ratio, enhanced mechanical properties, and impressive stability. Meanwhile, the microstructure of the GelMA/ColMA composite hydrogel showed a denser and interconnected microporous structure. In addition, the cytotoxicity study indicated that the GelMA/ColMA hydrogel has a cytocompatibility nature toward AMSCs. Finally, the fabrication of stem cell encapsulation hydrogels was studied, and the cells could be released continuously for more than 7 days with the normal cell function. The results of in vivo experiments indicated that the GelMA/ColMA/hAMSC (human amnion mesenchymal stem cell) hydrogel can prevent cavity adhesion in a rat IUA model. Therefore, bioprinting a biodegradable hydrogel cross-linked by blue light has satisfactory anticavity adhesion effects with excellent physical properties and biocompatibility, which could be used as a preventive barrier for intrauterine adhesion.

In Vitro Biological Performance of Alginate Hydrogel Capsules for Stem Cell Delivery.

Encapsulation of biological components in hydrogels is a well described method for controlled drug delivery of proteins, tissue engineering and intestinal colonization with beneficial bacteria. Given the potential of tissue engineering in clinical practice, this study aimed to evaluate the feasibility of encapsulation of adipose tissue-derived mesenchymal stem cells (MSCs) of mules in sodium alginate. We evaluated capsule morphology and cell viability, immunophenotype and release after encapsulation. Circular and irregular pores were observed on the hydrogel surface, in which MSCs were present and alive. Capsules demonstrated good capacity of absorption of liquid and cell viability was consistently high through the time points, indicating proper nutrient diffusion. Flow cytometry showed stability of stem cell surface markers, whereas immunohistochemistry revealed the expression of CD44 and absence of MHC-II through 7 days of culture. Stem cell encapsulation in sodium alginate hydrogel is a feasible technique that does not compromise cell viability and preserves their undifferentiated status, becoming a relevant option to further studies of tridimensional culture systems and in vivo bioactive agents delivery.