Deciphering the role of substrate stiffness to enhance internalization efficiency of plasmid DNA in stem cells using lipid-based nanocarriers

This study investigates the role of substrate stiffness on non-viral transfection of human adipose-derived stem cells (hASCs) with the aim to maximize hASCs expression of vascular endothelial growth factor (VEGF). The results confirm the direct effect of substrate stiffness in regulating cytoskeletal remodeling and corresponding plasmid internalization

Harnessing the Noncovalent Interactions of DNA Backbone with 2D Silicate Nanodisks To Fabricate Injectable Therapeutic Hydrogels

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/acsnano.8b02434.Injectable hydrogels present several advantages over prefabricated scaffolds including ease of delivery, shear-thinning property, and broad applicability in the fields of drug delivery and tissue engineering. Here, we report an approach to develop injectable hydrogels with sustained drug release properties, exploiting the chemical nature of the DNA backbone and silicate nanodisks. A two-step gelation method is implemented for generating a combination of noncovalent network points, leading to a physically cross-linked hydrogel. The first step initiates the development of an interconnected structure by utilizing DNA denaturation and rehybridization mechanism to form hydrogen bonds between complementary base pairs of neighboring DNA strands. The anisotropic charge distribution of two-dimensional silicate nanodisks (nSi) makes them an active center in the second step of the gelation process. Silicate nanodisks create additional network points via attractive electrostatic interactions with the DNA backbone, thereby enhancing the mechanical resilience of the formulated hydrogel. The thermally stable hydrogels displayed an increase in elasticity and yield stress as a function of nSi concentration. They were able to form self-supporting structures post injection due to their rapid recovery after removal of cyclic stress. Moreover, the presence of nanosilicate was shown to modulate the release of a model osteogenic drug dexamethasone (Dex). The bioactivity of released Dex was confirmed from in vitro osteogenic differentiation of human adipose stem cells and in vivo bone formation in a rat cranial bone defect model. Overall, our DNA-based nanocomposite hydrogel obtained from a combination of noncovalent network points can serve as an injectable material for bone regeneration and carrier for sustained release of therapeutics

Stem cell secretome-rich nanoclay hydrogel: a dual action therapy for cardiovascular regeneration†

A nanocomposite hydrogel with photocrosslinkable micro-porous networks and a nanoclay component was successfully prepared to control the release of growth factor-rich stem cell secretome. The proven pro-angiogenic and cardioprotective potential of this new bioactive system provides a valuable therapeutic platform for cardiac tissue repair and regeneration

Tailoring biomaterial surface properties to modulate host-implant interactions: implication in cardiovascular and bone therapy

Host body response to a foreign medical device plays a critical role in defining its fate post implantation. It is thus important to control host-material interactions by designing innovative implant surfaces. In the recent years, biochemical and topographical features have been explored as main target to produce this new type of bioinert or bioresponsive implants. The review discusses specific biofunctional materials and strategies to achieve a precise control over implant surface properties and presents possible solutions to develop next generation of implants, particularly in the fields of bone and cardiovascular therapy

Fabrication of a Double-Cross-Linked Interpenetrating Polymeric Network (IPN) Hydrogel Surface Modified with Polydopamine to Modulate the Osteogenic Differentiation of Adipose-Derived Stem Cells

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/acsami.8b05200.Hydrogel surface properties can be modified to form bioactive interfaces to modulate the osteogenic differentiation of stem cells. In this work, a hydrogel made of gelatin methacrylamide (GelMA) and alginate was designed and tested as a scaffold to control stem-cell osteogenic differentiation. The hydrogel’s surface was treated with polydopamine (pDA) to create an adhesive layer for the adsorption of the osteoinductive drug dexamethasone (Dex). The presence of the pDA coating enhanced Dex adsorption and retention over 21 days. This effect resulted in a delay in the osteogenic differentiation of hASCs cultured on the hydrogel treated with a pDA layer

Controlling Adult Stem Cell Behavior Using Nanodiamond-Reinforced Hydrogel: Implication in Bone Regeneration Therapy

Nanodiamonds (NDs) have attracted considerable attention as drug delivery nanocarriers due to their low cytotoxicity and facile surface functionalization. Given these features, NDs have been recently investigated for the fabrication of nanocomposite hydrogels for tissue engineering. Here we report the synthesis of a hydrogel using photocrosslinkable gelatin methacrylamide (GelMA) and NDs as a three-dimensional scaffold for drug delivery and stem cell-guided bone regeneration. We investigated the effect of different concentration of NDs on the physical and mechanical properties of the GelMA hydrogel network. The inclusion of NDs increased the network stiffness, which in turn augmented the traction forces generated by human adipose stem cells (hASCs). We also tested the ability of NDs to adsorb and modulate the release of a model drug dexamethasone (Dex) to promote the osteogenic differentiation of hASCs. The ND-Dex complexes modulated gene expression, cell area, and focal adhesion number in hASCs. Moreover, the integration of the ND-Dex complex within GelMA hydrogels allowed a higher retention of Dex over time, resulting in significantly increased alkaline phosphatase activity and calcium deposition of encapsulated hASCs. These results suggest that conventional GelMA hydrogels can be coupled with conjugated NDs to develop a novel platform for bone tissue engineering

Pre-Conditioning Stem Cells in a Biomimetic Environment for Enhanced Cardiac Tissue Repair: In Vitro and In Vivo Analysis

Introduction Stem cell-based therapies represent a valid approach to restore cardiac function due to their beneficial effect in reducing scar area formation and promoting angiogenesis. However, their translation into the clinic is limited by the poor differentiation and inability to secrete sufficient therapeutic factors. To address this issue, several strategies such as genetic modification and biophysical pre-conditioning have been used to enhance the efficacy of stem cells for cardiac tissue repair. Methods In this study, a biomimetic approach was used to mimic the natural mechanical stimulation of the myocardium tissue. Specifically, human adipose-derived stem cells (hASCs) were cultured on a thin gelatin methacrylamide (GelMA) hydrogel disc and placed on top of a beating cardiomyocyte layer. qPCR studies and metatranscriptomic analysis of hASCs gene expression were investigated to confirm the correlation between mechanical stimuli and cardiomyogenic differentiation. In vivo intramyocardial delivery of pre-conditioned hASCs was carried out to evaluate their efficacy to restore cardiac function in mice hearts post-myocardial infarction. Results The cyclic strain generated by cardiomyocytes significantly upregulated the expression of both mechanotransduction and cardiomyogenic genes in hASCs as compared to the static control group. The inherent angiogenic secretion profile of hASCs was not hindered by the mechanical stimulation provided by the designed biomimetic system. Finally, in vivo analysis confirmed the regenerative potential of the pre-conditioned hASCs by displaying a significant improvement in cardiac function and enhanced angiogenesis in the peri-infarct region. Conclusion Overall, these findings indicate that cyclic strain provided by the designed biomimetic system is an essential stimulant for hASCs cardiomyogenic differentiation, and therefore can be a potential solution to improve stem-cell based efficacy for cardiovascular repair

Investigation of human adipose-derived stem-cell behavior using a cell-instructive polydopamine-coated gelatin-alginate hydrogel.

Hydrogels can be fabricated and designed to exert direct control over stem cells\u27 adhesion and differentiation. In this study, we have investigated the use of polydopamine (pDA)-treatment as a binding platform for bioactive compounds to create a versatile gelatin-alginate (Gel-Alg) hydrogel for tissue engineering applications. Precisely, pDA was used to modify the surface properties of the hydrogel and better control the adhesion and osteogenic differentiation of human adipose-derived stem cells (hASCs). pDA enabled the adsorption of different types of bioactive molecules, including a model osteoinductive drug (dexamethasone) as well as a model pro-angiogenic peptide (QK). The pDA treatment efficiently retained the drug and the peptide compared to the untreated hydrogel and proved to be effective in controlling the morphology, cell area, and osteogenic differentiation of hASCs. Overall, the findings of this study confirm the efficacy of pDA treatment as a valuable strategy to modulate the biological properties of biocompatible Gel-Alg hydrogels and further extend their value in regenerative medicine

Multifunctional nanodiamonds in regenerative medicine: recent advances and future directions

With recent advances in the field of nanomedicine, many new strategies have emerged for diagnosing and treating diseases. At the forefront of this multidisciplinary research, carbon nanomaterials have demonstrated unprecedented potential for a variety of regenerative medicine applications including novel drug delivery platforms that facilitate the localized and sustained release of therapeutics. Nanodiamonds (NDs) are a unique class of carbon nanoparticles that are gaining increasing attention for their biocompatibility, highly functional surfaces, optical properties, and robust physical properties. Their remarkable features have established NDs as an invaluable regenerative medicine platform, with a broad range of clinically relevant applications ranging from targeted delivery systems for insoluble drugs, bioactive substrates for stem cells, and fluorescent probes for long-term tracking of cells and biomolecules in vitro and in vivo. This review introduces the synthesis techniques and the various routes of surface functionalization that allow for precise control over the properties of NDs. It also provides an in-depth overview of the current progress made toward the use of NDs in the fields of drug delivery, tissue engineering, and bioimaging. Their future outlook in regenerative medicine including the current clinical significance of NDs, as well as the challenges that must be overcome to successfully translate the reviewed technologies from research platforms to clinical therapies will also be discussed. © 2017 Elsevier B.V

Self-healing DNA-based injectable hydrogels with reversible covalent linkages for controlled drug delivery

Injectable hydrogels represent a valuable tool for the delivery of therapeutic molecules aimed to restore the functionality of damaged tissues. In this study, we report the design of a nanocomposite DNA-based hydrogel crosslinked with oxidized alginate (OA) via the formation of reversible imine linkages. The formulated hydrogel functioned as an injectable carrier for the sustained delivery of a small molecule drug, simvastatin. The degree of oxidation of alginate and the concentration of silicate-based nanoparticles (nSi) were varied to modulate the rheological properties of the hydrogels. Specifically, the formulations consisting of OA with higher degree of oxidation displayed the highest value of storage moduli, yield stress, yield strain, and rapid recovery after removal of cyclic stress. The hydrogel formulations exhibited self-healing and shear-thinning properties due to the reversible nature of the covalent imine bonds formed between the aldehyde groups of OA and the amine groups present in the DNA nucleotides. Moreover, the incorporation of charged nSi further enhanced the shear strength of the formulated hydrogels by establishing electrostatic interactions with the phosphate groups of the DNA network. The optimized hydrogel was able to promote the sustained release of simvastatin for more than a week. The bioactivity of the released drug was confirmed by testing its ability to induce osteogenic differentiation and migration of human adipose-derived stem cells in vitro. Overall, the results obtained from this study demonstrate that DNA could be used as a natural biopolymer to fabricate self-healing injectable hydrogels with sustained release properties for minimally invasive therapeutic approaches.Statement of significanceDynamic covalent chemistry, especially Schiff base reactions have emerged as a promising route for the formation of injectable hydrogels. Our study demonstrated the development of a DNA-based self-healing hydrogel formed via Schiff base reaction occurring at physiological conditions. The hydrogels functioned as sustained delivery vehicles for the hydrophobic drug simvastatin, which requires a polymeric carrier for controlled delivery of therapeutic concentrations of the drug without exhibiting cytotoxic effects. Presently available hydrogel-based drug delivery systems encounter major challenges for the delivery of hydrophobic drugs due to the hydrophilic nature of the base matrix. Our strategy presents a platform technology for the design of minimally invasive approaches for the sustained delivery of hydrophobic drugs similar to simvastatin. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved