Bone marrow-targetable Green Tea Catechin-Based Micellar Nanocomplex for synergistic therapy of Acute myeloid leukemia.

BACKGROUND: Currently available anti-leukemia drugs have shown limited success in the treatment of acute myeloid leukemia (AML) due to their poor access to bone marrow niche supporting leukemic cell proliferation. RESULTS: Herein, we report a bone marrow-targetable green tea catechin-based micellar nanocomplex for synergistic AML therapy. The nanocomplex was found to synergistically amplify the anti-leukemic potency of sorafenib via selective disruption of pro-survival mTOR signaling. In vivo biodistribution study demonstrated about 11-fold greater bone marrow accumulation of the nanocomplex compared to free sorafenib. In AML patient-derived xenograft (AML-PDX) mouse model, administration of the nanocomplex effectively eradicated bone marrow-residing leukemic blasts and improved survival rates without noticeable off-target toxicity. CONCLUSION: This study may provide insights into the rational design of nanomedicine platforms enabling bone marrow-targeted delivery of therapeutic agents for the treatment of AML and other bone marrow diseases.

Self-Assembled Daunorubicin/Epigallocatechin Gallate Nanocomplex for Synergistic Reversal of Chemoresistance in Leukemia.

Chemoresistance is one of the major challenges for the treatment of acute myeloid leukemia. Epigallocatechin gallate (EGCG), a bioactive polyphenol from green tea, has attracted immense interest as a potential chemosensitizer, but its application is limited due to the need for effective formulations capable of co-delivering EGCG and anti-leukemic drugs. Herein, we describe the formation and characterization of a micellar nanocomplex self-assembled from EGCG and daunorubicin, an anthracycline drug for the first-line treatment of acute myeloid leukemia. This nanocomplex was highly stable at pH 7.4 but stimulated to release the incorporated daunorubicin at pH 5.5, mimicking an acidic endosomal environment. More importantly, the nanocomplex exhibited superior cytotoxic efficacy against multidrug-resistant human leukemia cells over free daunorubicin by achieving a strong synergism, as supported by median-effect plot analysis. The observed chemosensitizing effect was in association with enhanced nucleus accumulation of daunorubicin, elevation of intracellular reactive oxygen species and caspase-mediated apoptosis induction. Our study presents a promising strategy for circumventing chemoresistance for more effective leukemia therapy.

Thiol-Mediated Synthesis of Hyaluronic Acid-Epigallocatechin-3-O-Gallate Conjugates for the Formation of Injectable Hydrogels with Free Radical Scavenging Property and Degradation Resistance.

Hyaluronic acid (HA)-based biomaterials have demonstrated only limited in vivo stability as a result of rapid degradation by hyaluronidase and reactive oxidative species. The green tea catechin, (-)-epigallocatechin-3-O-gallate (EGCG), has received considerable attention because of its powerful antioxidant and enzyme-inhibitory activities. We describe here the synthesis of HA-EGCG conjugate using a thiol-mediated reaction and its use for the preparation of a long-lasting injectable hydrogel. HA-EGCG conjugates with tunable degrees of substitution were synthesized by the nucleophilic addition reaction between EGCG quinone and thiolated HA under mild conditions. Contrary to unmodified HA, the conjugates exhibited free radical scavenging and hyaluronidase-inhibitory activities. Peroxidase-catalyzed coupling reaction between EGCG moieties was employed to produce in situ forming HA-EGCG hydrogel with surprisingly high resistance to hyaluronidase-mediated degradation. When injected subcutaneously in mice, HA-EGCG hydrogel was retained much longer than HA-tyramine hydrogel with minimal inflammation.

Chemotactic recruitment of adult neural progenitor cells into multifunctional hydrogels providing sustained SDF-1α release and compatible structural support.

Without chemotactic cues and structural support, cavitary brain lesions typically fail to recruit endogenous neural progenitor cells (NPCs). Toward resolving this, we engineered multifunctional biomaterials comprising injectable gelatin-hydroxyphenylpropionic acid (Gtn-HPA) hydrogels and dextran sulfate/chitosan polyelectrolyte complex nanoparticles (PCNs) that delivered stromal cell-derived factor-1α (SDF-1α). Over 7 d of interface with in vitro tissue simulant containing adult rat hippocampal NPCs (aNPCs) and their neuronal progeny, Gtn-HPA/SDF-1α-PCN hydrogels promoted chemotactic recruitment to enhance infiltration of aNPCs by 3- to 45-fold relative to hydrogels that lacked SDF-1α or vehicles to sustain SDF-1α release. When cross-linked with 0.85-0.95 mM HO, Gtn-HPA/SDF-1α-PCN hydrogels provided optimally permissive structural support for migration of aNPCs. Specific matrix metalloproteinase (MMP) inhibitors revealed that 42, 30, and 55% of cell migration into Gtn-HPA/SDF-1α-PCN hydrogels involved MMP-2, 3, and 9, respectively, demonstrating the hydrogels to be compatible toward homing endogenous NPCs, given their expression of similar MMPs. Interestingly, PCNs utilized FGF-2 found in situ to induce chemokinesis, potentiate SDF-1α chemotactic recruitment, and increase proliferation of recruited cells, which collectively orchestrated a higher number of migrated aNPCs. Overall, Gtn-HPA/SDF-1α-PCN hydrogels prove to be promising biomaterials for injection into cavitary brain lesions to recruit endogenous NPCs and enhance neural tissue repair/regeneration.

Potentiating Gilteritinib Efficacy Using Nanocomplexation with a Hyaluronic Acid-Epigallocatechin Gallate Conjugate.

Acute myeloid leukemia carrying FMS-like tyrosine kinase receptor-3 (FLT3) mutations is a fatal blood cancer with a poor prognosis. Although the FLT3 inhibitor gilteritinib has recently been approved, it still suffers from limited efficacy and relatively high nonresponse rates. In this study, we report the potentiation of gilteritinib efficacy using nanocomplexation with a hyaluronic acid-epigallocatechin gallate conjugate. The self-assembly, colloidal stability, and gilteritinib loading capacity of the nanocomplex were characterized by reversed-phase high-performance liquid chromatography and dynamic light scattering technique. Flow cytometric analysis revealed that the nanocomplex efficiently internalized into FLT3-mutated leukemic cells via specific interactions between the surface-exposed hyaluronic acid and CD44 receptor overexpressed on the cells. Moreover, this nanocomplex was found to induce an eradication of the leukemic cells in a synergistic manner by elevating the levels of reactive oxygen species and caspase-3/7 activities more effectively than free gilteritinib. This study may provide a useful strategy to design nanomedicines capable of augmenting the therapeutic efficacy of FLT3 inhibitors for effective leukemia therapy.

Oxidation as a facile strategy to reduce the surface charge and toxicity of polyethyleneimine gene carriers.

Polyethyleneimine (PEI) is widely regarded as one of the most efficient non-viral transfection agents commercially available. However, a key concern is its pronounced cytotoxicity, ascribed mainly to its high amine content and cationic charge density. Significant past efforts to mitigate its toxicity usually involved lengthy synthetic procedures. We now propose a simple strategy using hydrogen peroxide (H2O2) to oxidize the amine groups. PEI/DNA complexes were first formed before some amine groups were removed with H2O2. This reduced surface charge while the remaining cationic charges still allowed for efficient transfection. The DNA was not damaged and remained bound after oxidation. Furthermore, H2O2 was quantitatively removed with sodium pyruvate prior to cell culture. Oxidized complexes caused no cytotoxicity even at high polymer concentrations. Compared to non-oxidized complexes used at subtoxic doses, oxidized complexes mediated significantly more GFP expression. A key strength of this approach is its simplicity as it involves only simple mixing of solutions. This strategy promises to further realize the potential of using PEI for the delivery of nucleic acids or other cargos.

Mechano-Chemical Effect of Gelatin- and HA-Based Hydrogels on Human Retinal Progenitor Cells.

Engineering matrices for cell therapy requires design criteria that include the ability of these materials to support, protect and enhance cellular behavior in vivo. The chemical and mechanical formulation of the biomaterials can influence not only target cell phenotype but also cellular differentiation. In this study, we have demonstrated the effect of a gelatin (Gtn)-hyaluronic acid (HA) hydrogel on human retinal progenitor cells (hRPCs) and show that by altering the mechanical properties of the materials, cellular behavior is altered as well. We have created an interpenetrating network polymer capable of encapsulating hRPCs. By manipulating the stiffness of the hydrogel, the differentiation potential of the hRPCs was controlled. Interpenetrating network 75 (IPN 75; 75% HA) allowed higher expression of rod photoreceptor markers, whereas cone photoreceptor marker expression was found to be higher in IPN 50. In vivo testing of these living matrices performed in Long-Evans rats showed higher levels of rod photoreceptor marker expression when IPN 75 was injected versus IPN 50. These biomaterials mimic biological cues that are required to simulate the dynamic complexity of natural retinal ECM. These hydrogels can be used as a vehicle for cell delivery in vivo as well as for expansion and differentiation in an in vitro 3D system in a highly reproducible manner.

Toxicity and efficacy of green tea catechin derivative-based micellar nanocomplexes for anticancer protein delivery.

Toxicity towards non-tumor cells during anticancer therapy can be reduced by using nanoscale systems for anticancer drug delivery. Usually only the loaded drug has anticancer activity. Recently, micellar nanocomplexes (MNCs) comprising green tea catechin derivatives for the delivery of the anticancer proteins, such as Herceptin, have been developed. Herceptin as well as the MNCs without the drug were effective against HER2/neu-overexpressing human tumor cells and had synergistic anticancer effects in vitro and in vivo. It remained unclear which kinds of negative effects the MNCs had on tumor cells exactly, and which of their components mediated them. Also, it was unclear if MNC has any toxicity effects on the normal cells of vital human organ systems. Herein we examined the effects of Herceptin-MNCs and their individual components on human breast cancer cells and on normal primary human endothelial and kidney proximal tubular cells. We applied a novel in vitro model that predicts nephrotoxicity in humans with high accuracy, as well as high-content screening and microfluidic mono- and co-culture models to thoroughly address effects on various cell types. The results showed that MNCs alone were profoundly toxic for breast cancer cells, and induced apoptosis regardless of HER2/neu expression levels. Apoptosis was induced by both green tea catechin derivatives contained within MNCs. In contrast, MNCs were not toxic for normal human cells, and the probability was low that MNCs would be nephrotoxic in humans. Together, the results supported the hypothesis that green tea catechin derivative-based MNCs could improve efficacy and safety of therapies with anticancer proteins.

Autoxidation-Resistant, ROS-Scavenging, and Anti-Inflammatory Micellar Nanoparticles Self-Assembled from Poly(acrylic acid)-Green Tea Catechin Conjugates.

(-)-Epigallocatechin-3-O-gallate (EGCG), the most bioactive catechin in green tea, has drawn significant interest as a potent antioxidant and anti-inflammatory compound. However, the application of EGCG has been limited by its rapid autoxidation at physiological pH, which generates cytotoxic levels of reactive oxygen species (ROS). Herein, we report the synthesis of poly(acrylic acid)-EGCG conjugates with tunable degrees of substitution and their spontaneous self-assembly into micellar nanoparticles with enhanced resistance against autoxidation. These nanoparticles not only exhibited superior oxidative stability and cytocompatibility over native EGCG, but also showed excellent ROS-scavenging and anti-inflammatory effects. This work presents a potential strategy to overcome the stability and cytotoxicity issues of EGCG, making it one step closer toward its widespread application.

Platelet-Rich Plasma Lysate-Incorporating Gelatin Hydrogel as a Scaffold for Bone Reconstruction.

In implant dentistry, large vertical and horizontal alveolar ridge deficiencies in mandibular and maxillary bone are challenges that clinicians continue to face. One of the limitations of porous blocks for reconstruction of bone in large defects in the oral cavity, and in the musculoskeletal system, is that fibrin clot does not adequately fill the interior pores and does not persist long enough to accommodate cell migration into the center of the block. The objective of our work was to develop a gelatin-based gel incorporating platelet-rich plasma (PRP) lysate, to mimic the role that a blood clot would normally play to attract and accommodate the migration of host osteoprogenitor and endothelial cells into the scaffold, thereby facilitating bone reconstruction. A conjugate of gelatin (Gtn) and hydroxyphenyl propionic acid (HPA), an amino-acid-like molecule, was commended for this application because of its ability to undergo enzyme-mediated covalent cross-linking to form a hydrogel in vivo, after being injected as a liquid. The initiation and propagation of cross-linking were under the control of horseradish peroxidase and hydrogen peroxide, respectively. The objectives of this in vitro study were directed toward evaluating: (1) the migration of rat mesenchymal stem cells (MSCs) into Gtn-HPA gel under the influence of rat PRP lysate or recombinant platelet-derived growth factor (PDGF)-BB incorporated into the gel; (2) the differentiation of MSCs, incorporated into the gel, into osteogenic cells under the influence of PRP lysate and PDGF-BB; and (3) the release kinetics of PDGF-BB from gels incorporating two formulations of PRP lysate and recombinant PDGF-BB. Results: The number of MSCs migrating into the hydrogel was significantly (3-fold) higher in the hydrogel group incorporating PRP lysate compared to the PDGF-BB and the blank gel control groups. For the differentiation/osteogenesis assay, the osteocalcin-positive cell area percentage was significantly higher in both the gel/PRP and gel/PDGF-BB groups, compared to the two control groups: cells in the blank gels grown in cell expansion medium and in osteogenic medium. Results of the ELISA release assay indicated that Gtn-HPA acted as an effective delivery vehicle for the sustained release of PDGF-BB from two different PRP lysate batches, with about 60% of the original PDGF-BB amount in the two groups remaining in the gel at 28 days. Conclusions: Gtn-HPA accommodates MSC migration. PRP-lysate-incorporating hydrogels chemoattract increased MSC migration into the Gtn-HPA compared to the blank gel. PRP-lysate- and the PDGF-BB-incorporating gels stimulate osteogenic differentiation of the MSCs. The release of the growth factors from Gtn-HPA containing PRP lysate can extend over the period of time (weeks) necessary for bone reconstruction. The findings demonstrate that Gtn-HPA can serve as both a scaffold for cell migration and a delivery vehicle that allows sustained and controlled release of the incorporated therapeutic agent over extended periods of time. These findings commend Gtn-HPA incorporating PRP lysate for infusion into porous calcium phosphate blocks for vertical and horizontal ridge reconstruction, and for other musculoskeletal applications.

Green tea catechin-grafted silk fibroin hydrogels with reactive oxygen species scavenging activity for wound healing applications.

BACKGROUND: Overproduction of reactive oxygen species (ROS) is known to delay wound healing by causing oxidative tissue damage and inflammation. The green tea catechin, (-)-Epigallocatechin-3-O-gallate (EGCG), has drawn a great deal of interest due to its strong ROS scavenging and anti-inflammatory activities. In this study, we developed EGCG-grafted silk fibroin hydrogels as a potential wound dressing material. METHODS: The introduction of EGCG to water-soluble silk fibroin (SF-WS) was accomplished by the nucleophilic addition reaction between lysine residues in silk proteins and EGCG quinone at mild basic pH. The resulting SF-EGCG conjugate was co-crosslinked with tyramine-substituted SF (SF-T) via horseradish peroxidase (HRP)/H2O2 mediated enzymatic reaction to form SF-T/SF-EGCG hydrogels with series of composition ratios. RESULTS: Interestingly, SF-T70/SF-EGCG30 hydrogels exhibited rapid in situ gelation (< 30 s), similar storage modulus to human skin (≈ 1000 Pa) and superior wound healing performance over SF-T hydrogels and a commercial DuoDERM® gel dressings in a rat model of full thickness skin defect. CONCLUSION: This study will provide useful insights into a rational design of ROS scavenging biomaterials for wound healing applications.

Integrating biomaterials and food biopolymers for cultured meat production.

Cultured meat has recently achieved mainstream prominence due to the emergence of societal and industrial interest. In contrast to animal-based production of traditional meat, the cultured meat approach entails laboratory cultivation of engineered muscle tissue. However, bioengineers have hitherto engineered tissues to fulfil biomedical endpoints, and have had limited experience in engineering muscle tissue for its post-mortem traits, which broadly govern consumer definitions of meat quality. Furthermore, existing tissue engineering approaches face fundamental challenges in technical feasibility and industrial scalability for cultured meat production. This review discusses how animal-based meat production variables influence meat properties at both the molecular and functional level, and whether current cultured meat approaches recapitulate these properties. In addition, this review considers how conventional meat producers employ exogenous biopolymer-based meat ingredients and processing techniques to mimic desirable meat properties in meat products. Finally, current biomaterial strategies for engineering muscle and adipose tissue are surveyed in the context of emerging constraints that pertain to cultured meat production, such as edibility, sustainability and scalability, and potential areas for integrating biomaterials and food biopolymer approaches to address these constraints are discussed. STATEMENT OF SIGNIFICANCE: Laboratory-grown or cultured meat has gained increasing interest from industry and the public, but currently faces significant impediment to market feasibility. This is due to fundamental knowledge gaps in producing realistic meat tissues via conventional tissue engineering approaches, as well as translational challenges in scaling up these approaches in an efficient, sustainable and high-volume manner. By defining the molecular basis for desirable meat quality attributes, such as taste and texture, and introducing the fundamental roles of food biopolymers in mimicking these properties in conventional meat products, this review aims to bridge the historically disparate fields of meat science and biomaterials engineering in order to inspire potentially synergistic strategies that address some of these challenges.

Hyaluronic acid-green tea catechin conjugates as a potential therapeutic agent for rheumatoid arthritis.

Fibroblast-like synoviocytes are a key effector cell type involved in the pathogenesis of rheumatoid arthritis. The major green tea catechin, epigallocatechin-3-O-gallate (EGCG), has attracted significant interest for rheumatoid arthritis therapy because of its ability to suppress the proliferation and interleukin-6 secretion of synoviocytes. However, therapeutic efficacy of EGCG has been limited by a lack of target cell specificity. Herein we report hyaluronic acid-EGCG (HA-EGCG) conjugates as an anti-arthritic agent that is capable of targeting fibroblast-like synoviocytes via HA-CD44 interactions. These conjugates exhibited superior anti-proliferative and anti-inflammatory activities compared with EGCG under simulated physiological conditions. Near-infrared fluorescence imaging revealed preferential accumulation of the conjugates at inflamed joints in a collagen-induced arthritis rat model, and their anti-arthritic efficacy was investigated by measuring a change in the edema and histopathological scores. Our findings suggest the potential of HA-EGCG conjugates as an anti-arthritic agent for the treatment of rheumatoid arthritis.

An Injectable Multifunctional Dual-Phase Bead-Reinforced Gelatin Matrix Permissive of Mesenchymal Stem Cell Infiltration for Musculoskeletal Soft Tissue Repair.

This study develops a novel strategy for regenerative therapy of musculoskeletal soft tissue defects using a dual-phase multifunctional injectable gelatin-hydroxyphenyl propionic acid (Gtn-HPA) composite. The dual-phase gel consists of stiff, degradation-resistant, ≈2-mm diameter spherical beads made from 8 wt% Gtn-HPA in a 2 wt% Gtn-HPA matrix. The results of a 3D migration assay show that both the cell number and migration distance in the dual-phase gel system are comparable with the 2 wt% mono-phase Gtn-HPA, but notably significantly higher than for 8 wt% mono-phase Gtn-HPA (into which few cells migrated). The results also show that the dual phase gel system has degradation resistance and a prolonged growth factor release profile comparable with 8 wt% mono-phase Gtn-HPA. In addition, the compressive modulus of the 2 wt% dual-phase gel system incorporating the 8 wt% bead phase is nearly four-fold higher than the 2 wt% mono-phase gel (5.3 ± 0.4 kPa versus 1.5 ± 0.06 kPa). This novel injectable dual-phase Gtn-HPA composite thus combines the advantages of low-concentration Gtn-HPA (cell migration) with high-concentration Gtn-HPA (stiffness, degradation resistance, slower chemical release kinetics) to facilitate effective reparative/regenerative processes in musculoskeletal soft tissue.

Platelet-Derived Growth Factor Stimulated Migration of Bone Marrow Mesenchymal Stem Cells into an Injectable Gelatin-Hydroxyphenyl Propionic Acid Matrix.

Bone marrow mesenchymal stem cells (bMSCs) are responsible in the repair of injured tissue through differentiation into multiple cell types and secretion of paracrine factors, and thus have a broad application profile in tissue engineering/regenerative medicine, especially for the musculoskeletal system. The lesion due to injury or disease may be a closed irregular-shaped cavity deep within tissue necessitating an injectable biomaterial permissive of host (endogenous) cell migration, proliferation and differentiation. Gelatin-hydroxyphenyl propionic acid (Gtn-HPA) is a natural biopolymer hydrogel which is covalently cross-linked by horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) in situ and can be delivered to the lesion by needle injection. Growth factors and cytokines can be directly incorporated into the gel or into nano- and micro-particles, which can be employed for sustained release of biomolecules while maintaining their bioactivity. In this study, we selected polyelectrolyte complex nanoparticles (PCNs) prepared with dextran sulfate and chitosan as the carrier for platelet-derived growth factor (PDGF)-BB and stromal cell-derived factor (SDF)-1α, which have been tested effectively in recruiting stem cells. Our in vitro results showed a high degree of viability of bMSCs through the process of Gtn-HPA covalent cross-linking gelation. The Gtn-HPA matrix was highly permissive of bMSC migration, proliferation, and differentiation. PDGF-BB (20 ng/mL) directly incorporated into the gel and, alternatively, released from PCNs stimulated bMSC migration and proliferation. There were only small differences in the results for the direct incorporation of PDGF into the gel compared with its release from PCNs, and for increased doses of the growth factor (200 ng/mL and 2 µg/mL). In contrast, SDF-1α elicited an increase in migration and proliferation only when released from PCNs; its effect on migration was notably less than PDGF-BB. The in vitro results demonstrate that PDGF-BB substantially increases migration of bMSCs into Gtn-HPA and their proliferation in the gel, and that these benefits can be derived from incorporation of a relatively low dose of the growth factor directly into the gel. These findings commend the use of Gtn-HPA/PDGF-BB as an injectable therapeutic agent to treat defects in musculoskeletal tissues.

A bioinspired gelatin-hyaluronic acid-based hybrid interpenetrating network for the enhancement of retinal ganglion cells replacement therapy.

Biomaterial-based cell replacement approaches to regenerative medicine are emerging as promising treatments for a wide array of profound clinical problems. Here we report an interpenetrating polymer network (IPN) composed of gelatin-hydroxyphenyl propionic acid and hyaluronic acid tyramine that is able to enhance intravitreal retinal cell therapy. By tuning our bioinspired hydrogel to mimic the vitreous chemical composition and mechanical characteristics we were able to improve in vitro and in vivo viability of human retinal ganglion cells (hRGC) incorporated into the IPN. In vivo vitreal injections of cell-bearing IPN in rats showed extensive attachment to the inner limiting membrane of the retina, improving with hydrogels stiffness. Engrafted hRGC displayed signs of regenerating processes along the optic nerve. Of note was the decrease in the immune cell response to hRGC delivered in the gel. The findings compel further translation of the gelatin-hyaluronic acid IPN for intravitreal cell therapy.

The effects of shock wave stimulation of mesenchymal stem cells on proliferation, migration, and differentiation in an injectable gelatin matrix for osteogenic regeneration.

The treatment of a variety of defects in bony sites could benefit from mitogenic stimulation of osteoprogenitor cells, including endogenous bone marrow-derived mesenchymal stem cells (bMSCs), and from provision of such cells with a matrix permissive of their migration, proliferation, and osteogenic differentiation. That such MSC stimulation could result from treatment with noninvasive (extracorporeal) shock waves (ESWs), and the matrix delivered by injection could enable this therapeutic approach to be employed for applications in which preformed scaffolds and growth factor therapy are difficult to deploy. The objectives of the present study were to investigate focused ESWs for their effects on proliferation, migration, and osteogenic differentiation in an injectable gelatin (Gtn) matrix capable of undergoing covalent cross-linking in vivo. Gtn was conjugated with hydroxyphenyl propionic acid (HPA) in order to enable it to be covalently cross-linked with minute amounts of horseradish peroxidase and hydrogen peroxide. The results demonstrated that 500 shocks of 0.4-mJ/mm2 energy flux density resulted in a twofold greater proliferation of bMSCs in the Gtn-HPA matrix after 14 days, compared with bMSCs grown with supplementation with platelet-derived growth factor (PDGF)-BB, a known mitogen for bMSCs. Moreover, SW treatment enhanced substantially osteogenic differentiation of bMSCs. The Gtn-HPA gel was permissive of MSC migration under the chemotactic influence of the growth factor, PDGF-BB, incorporated into and released by the gel. ESW treatment had no effect on the motility of the MSCs. The findings of the study warrant further investigation of this combined treatment modality for select bony defects.

Hydrogel-Based Therapy for Brain Repair After Intracerebral Hemorrhage.

We assessed an injectable gelatin hydrogel containing epidermal growth factor (Gtn-EGF) as a therapy for intracerebral hemorrhage (ICH). ICH was induced in rats via collagenase injection into the striatum. Two weeks later, Gtn-EGF was injected into the cavitary lesion. The hydrogel filled ICH cavities without deforming brain tissue. Immunostaining demonstrated that neural precursor cells could migrate into the matrix, and some of these differentiated into neurons along with the appearance of astrocytes, oligodendrocytes, and endothelial cells. Sensorimotor tests suggested that Gtn-EGF improved neurological recovery. This study provides proof-of-principle that injectable biomaterials may be a translationally relevant approach for treating ICH.

Hyaluronic acid hydrogels with defined crosslink density for the efficient enrichment of breast cancer stem cells.

Cancer stem cells (CSCs) have been much proposed as potential tumor eradication targets since they possess highly tumorigenic qualities. However, efficient and fast enrichment of CSCs for cancer biology study and drug screening has been challenging. CD44 is a cell surface receptor for hyaluronic acid (HA) and has been reported as an important CSC marker. Here, we show a simple and label-free method for the enrichment of CSCs highly expressing CD44 using enzymatically crosslinked HA hydrogels. HA hydrogels were formed with different crosslink densities to modulate the interaction between the CD44 and HA chains. We show that HA hydrogels with defined crosslink densities isolated cancer cells expressing high CD44 from breast cancer cell lines in a facile, efficient manner. The enriched cells exhibited CSC-like characteristics such as high expression of CSC markers (octamer-binding transcription factor 4 (OCT4) and aldehyde dehydrogenase 1 (ALDH1)), enhanced tumorsphere formation and chemoresistance. The enriched cells also displayed strong tumorigenicity, metastatic potential and poor survival in vivo. The HA hydrogel provides a simple, fast and efficient platform for CSC enrichment and promotes new anticancer strategies that target breast CSCs. STATEMENT OF SIGNIFICANCE: There is strong interest in developing isolation methods for cancer stem cells (CSCs), due in growing desire for CSC eradication for promising cancer therapy. Tumor sphere formation and fluorescence-activated cell sorting have been widely used for CSC isolation, while these methods require cultivation for several days and labelling of cell surface proteins, respectively. A simple and label-free method for breast CSC isolation is developed using HA-based hydrogels with tunable crosslink density. The efficient enrichment of breast CSCs is achieved by HA-CD44 specific interaction, which is controlled by hydrogel crosslink density. We believe that the simple approach that isolates cells with CSC-like characteristics would facilitate the anticancer drug development and cancer research.

Mechanically and chemically defined hydrogel matrices for patient-derived colorectal tumor organoid culture.

Patient-derived tumor organoids offer potentially useful models of cancer tissue physiology. Yet, conventional organoid cultures utilize generic matrices that are difficult to tailor for various unique tumor microenvironments. Here, we employ synthetic, enzymatically crosslinked hydrogels to define mechanical and biochemical properties hypothesized to be relevant for maintaining these organoids. We show that a single extracellular matrix component, gelatin, suffices to support colorectal cancer patient-derived xenograft (CRC-PDX) organoid survival, and that high matrix stiffness synergizes with hypoxia to increase organoid growth and metabolism in a majority of CRC-PDX lines tested. Moreover, we demonstrate that defined gelatin-based hydrogels support CRC-PDX tumor growth in vivo and organoid sensitivity to various CRC therapeutic drugs in vitro in a largely comparable fashion to a conventional reconstituted basement membrane matrix. Based on our findings, we propose that enzymatically crosslinked hydrogels potentially provide a platform for designing mechanically and biochemically defined matrices for various types of patient-derived tumor organoids.