Covalent Cell‐Loading Injectable Hydrogel Scaffold Significantly Promotes Tissue Regeneration In Vivo Compared with a Conventional Physical Cell‐Loading Hydrogel Scaffold

Tumor cell loaded thermosensitive hydrogel for photodynamic therapy associated tumor antigens release

BACKGROUND

Immunotherapy is a powerful strategy for treating cancer and can be used to inhibit the post-surgical relapse of tumors.

METHODS

To achieve this, a Cell@hydrogel was developed as a template using a mixture of CT26 tumor cells and Pluronic® F-127/gelatin.

RESULTS

The proposed mixture has a solution-to-gelation functionality and vice versa. The morphology of the Cell@hydrogel was characterized by scanning electron microscopy and confocal microscopy. For photodynamic immunotherapy, the Cell@hydrogel was functionalized with Cy7 (Cy7-Cell@hydrogel) to quantify reactive oxygen species in CT26 tumor cells. Gel electrophoresis and membrane integrity tests were performed to determine the efficiency of the Cy7-Cell@hydrogel following photodynamic therapy.

CONCLUSIONS

This protocol provides an alternative approach that mechanistically inhibits the post-surgical relapse of solid tumors based on immunotherapy.

Advances in Cell-Rich Inks for Biofabricating Living Architectures

Advancing biofabrication toward manufacturing living constructs with well-defined architectures and increasingly biologically relevant cell densities is highly desired to mimic the biofunctionality of native human tissues. The formulation of tissue-like, cell-dense inks for biofabrication remains, however, challenging at various levels of the bioprinting process. Promising advances have been made toward this goal, achieving relatively high cell densities that surpass those found in conventional platforms, pushing the current boundaries closer to achieving tissue-like cell densities. On this focus, herein the overarching challenges in the bioprocessing of cell-rich living inks into clinically grade engineered tissues are discussed, as well as the most recent advances in cell-rich living ink formulations and their processing technologies are highlighted. Additionally, an overview of the foreseen developments in the field is provided and critically discussed.

Pluronic F-68 and F-127 Based Nanomedicines for Advancing Combination Cancer Therapy

Pluronics are amphiphilic triblock copolymers composed of two hydrophilic poly (ethylene oxide) (PEO) chains linked via a central hydrophobic polypropylene oxide (PPO). Owing to their low molecular weight polymer and greater number of PEO segments, Pluronics induce micelle formation and gelation at critical micelle concentrations and temperatures. Pluronics F-68 and F-127 are the only United States (U.S.) FDA-approved classes of Pluronics and have been extensively used as materials for living bodies. Owing to the fascinating characteristics of Pluronics, many studies have suggested their role in biomedical applications, such as drug delivery systems, tissue regeneration scaffolders, and biosurfactants. As a result, various studies have been performed using Pluronics as a tool in nanomedicine and targeted delivery systems. This review sought to describe the delivery of therapeutic cargos using Pluronic F-68 and F-127-based cancer nanomedicines and their composites for combination therapy.

Tissue engineering modalities in skeletal muscles: focus on angiogenesis and immunomodulation properties

Muscular diseases and injuries are challenging issues in human medicine, resulting in physical disability. The advent of tissue engineering approaches has paved the way for the restoration and regeneration of injured muscle tissues along with available conventional therapies. Despite recent advances in the fabrication, synthesis, and application of hydrogels in terms of muscle tissue, there is a long way to find appropriate hydrogel types in patients with congenital and/or acquired musculoskeletal injuries. Regarding specific muscular tissue microenvironments, the applied hydrogels should provide a suitable platform for the activation of endogenous reparative mechanisms and concurrently deliver transplanting cells and therapeutics into the injured sites. Here, we aimed to highlight recent advances in muscle tissue engineering with a focus on recent strategies related to the regulation of vascularization and immune system response at the site of injury.

Covalent Stem Cell-Combining Injectable Materials with Enhanced Stemness and Controlled Differentiation In Vivo

Biohybrid materials, which are defined as engineered functional materials combining living components with nonliving synthetic materials, are considered promising bioactive materials for applications in in vivo tissue engineering. However, the rational design of biohybrid materials applicable to in vivo tissue engineering faces major challenges associated with techniques for combining living cells with nonliving synthetic materials and cell sources. Here, we report injectable covalent stem cell-combing biohybrid materials prepared via a bio-orthogonal click cross-linking reaction of azide-modified adipose-derived stem cells (N₃[+]ADSCs), one of the most promising cell sources utilized clinically, with alkyne-modified biocompatible alginate polymers. The mechanical properties of the covalent stem cell-combining biohybrid materials can be adapted to the mechanical properties of the surrounding environment in which they are transplanted by alternating the number of N₃[+]ADSCs, the concentration of alkyne-modified alginate, and the number of alkyne groups. Importantly, ADSCs in the covalent biohybrid materials expressed a high level of CD-105, a marker for undifferentiated mesenchymal stem cells, in the body in the absence of differentiation signals, whereas very little CD-105 was expressed in the control physical cell-loading materials, demonstrating that this covalent stem cell-combining approach results in enhanced retention of the material's "stemness" and controlled differentiation in the body. We assessed the potential utility of the covalent stem cell-combining biohybrid materials for in vivo tissue engineering using a murine severe skeletal muscle defect-healing model. Importantly, all of the tissues regenerated by the covalent biohybrid material treatment expressed MYH3, a myogenic marker protein, whereas no expression of MYH3 was detected in the tissues reconstructed by treatment with control physical stem cell-loading materials and Matrigel, indicating that this covalent stem cell-combining approach results in controlled differentiation in the body. Our data demonstrate the potential utility of covalent stem cell-combining biohybrid materials with host tissue-integrative and controlled differentiation capabilities available for in vivo tissue engineering.

Biological Tissue-Inspired Living Self-Healing Hydrogels Based on Cadherin-Mediated Specific Cell-Cell Adhesion

Regarding synthetic self-healing materials, as healing reactions occur at the molecular level, bond formation occurs when healing chemicals are nanometer distances apart. However, motility of healing chemicals in materials is quite limited, permitting only passive diffusion, which reduces the chance of bond formation. By contrast, biological-tissues exhibit significant high-performance self-healing, and cadherin-mediated cell-cell adhesion is a key mechanism in the healing process. This is because cells are capable of a certain level of motility and actively migrate to damage sites, thereby achieving cell-cell adhesion with high efficacy. Here, we report biological-tissue-inspired, self-healing hydrogels in which azide-modified living cells are covalently cross-linked with alkyne-modified alginate polymers via bioorthogonal reactions. As a proof-of-concept, we demonstrate their unique self-healing capabilities originating from cadherin-mediated adhesion between cells incorporated into the gels as mobile healing mechanism. This study provides an example of self-healing material incorporating living components into a synthetic material to promote self-healing.