Thermosensitive hydrogels functionalized with pH sensitive COOH groups for bone cell harvesting

Development of Thermosensitive Hydrogels with Tailor-Made Geometries to Modulate Cell Harvesting of Non-Flat Cell Cultures

Considering the complexity in terms of design that characterizes the different tissues of the human body, it is necessary to study and develop more precise therapies. In this sense, this article presents the possibility of fabricating photocurable thermosensitive hydrogels with free geometry and based on N-Vinyl Caprolactam (VCL) with the aim of modulating the adhesion of non-planar cell cultures. The fabrication process is based on the use as a mold of two-layer thick water-soluble polyvinyl alcohol (PVA) previously printed by Extrusion Material (MatEx). From this technology it has been possible to obtain hydrogels with different 3D geometries and different crosslinking percentages (2, 4 and 6 mol%). Studies have shown that networks reduce their thermosensitivity not only when the percentage of crosslinking in the formulation increases, but also when the thickness of the hydrogel obtained increases. Based on this reduction in thermosensitivity, the less crosslinked (2 mol%) hydrogels have been evaluated to carry out a novel direct application in which hydrogels with curved geometry have allowed cell adhesion and proliferation at 37 °C with the endothelial cell line C166-GFP; likewise, non-aggressive cell detachment was observed when the hydrogel temperature was reduced to values of 20 °C. Therefore, the present manuscript shows a novel application for the synthesis of free-form thermosensitive hydrogels that allows modulation of non-planar cell cultures.

Osteoblastic Cell Sheet Engineering Using P(VCL-HEMA)-Based Thermosensitive Hydrogels Doped with pVCL@Icariin Nanoparticles Obtained with Supercritical CO2-SAS

New clinical strategies for treating severe bone and cartilage injuries are required, especially for use in combination with implant procedures. For this purpose, p(VCL-co-HEMA) thermosensitive hydrogels have been activated with icariin-loaded nanoparticles to be used as bone-cell-harvesting platforms. Supercritical CO2-SAS technology has been applied to encapsulate icariin, a small molecule that is involved in osteoblastic differentiation. Thus, physical-chemical analysis, including swelling and transmittance, showed the impact of HEMA groups in hydrogel composition. Moreover, icariin (ICA) release from p(VCL-co-HEMA) platforms, including pVCL@ICA nanoparticles, has been studied to evaluate their efficacy in relevant conditions. Finally, the thermosensitive hydrogels' cell compatibility, transplant efficiency, and bone differentiation capacity were tested. This study identifies the optimal formulations for icariin-activated hydrogels for both control and HEMA formulations. Using this technique, osteoblastic sheets that were rich in collagen type I were successfully transplanted and recultivated, maintaining an optimal extracellular matrix (ECM) composition. These findings suggest a new cell-sheet-based therapy for bone regeneration purposes using customized and NP-activated pVCL-based cell platforms.

Recent advancements of hydrogels in immunotherapy: Breast cancer treatment

Breast cancer is the most prevalent cancer among women and the leading cause of cancer-related deaths in this population. Recent advances in Immunotherapy, or combined immunotherapy, offering a more targeted and less toxic approach, expand the survival rate of patients more than conventional treatment. Notably, hydrogels, a versatile platform provided promising avenues to combat breast cancer in preclinical studies and extended to clinical practices. With advantages such as the alternation of tumor microenvironment, immunomodulation, targeted delivery of therapeutic agents, and their sustained release at specific sites of interest, hydrogels can potentially be used for the treatment of breast cancer. This review highlights the advantages, mechanisms of action, stimuli-responsiveness properties, and recent advancements of hydrogels for treating breast cancer immunotherapy. Moreover, post-treatment and its clinical translations are discussed in this review. The integration of hydrogels in immunotherapy strategies may pave the way for more effective, personalized, and patient-friendly approaches to combat breast cancer, ultimately contributing to a brighter future for breast cancer patients.

Hydrogels with dual sensitivity to temperature and pH in physiologically relevant ranges as supports for versatile controlled cell detachment

Thermosensitive hydrogels based on the N-vinyl caprolactam (VCL), capable of allowing for cell adhesion and proliferation, as well as non-aggressive detachment by controlled temperature drop, were functionalized with 23 % or lower molar percentages of the cationizable hydrophobic unit 2-(diisopropylamino) ethyl methacrylate (DPAEMA), to obtain networks with dual sensitivity to temperature and pH. The swelling analysis of the systems has shown a transition pK (pKb) close to physiological values, dependent on the temperature of the medium (pKb of 6.6 and 6.9 when the temperature of the medium is above and below the transition temperature VPTT, respectively) and little dependence on the degree of functionalization of DPAEMA. In addition, at temperatures below the transition temperature (VPTT), the systems have shown large swelling variations as a function of the pH (i.e. below and above the pKb), exhibiting greater absorption capacity at pHs below pKb, where the DPAEMA units are cationized. Cytocompatibility and transplant capacity have been evaluated using the C166-GFP endothelial cell line. None of the thermosensitive hydrogels with variable DPAEMA content showed a delay with respect to the control without DPAEMA neither in terms of adhesion nor in proliferation. However, by increasing the percentage of DPAEMA functionalization -and decreasing thermosensitivity-, a correlative decrease in mitochondrial activity was obtained in the transplant, with significant differences for the hydrogels with DPAEMA molar percentage of 3 % or higher. Taking advantage of the proximity of the pKb to the physiological value, we have evaluated the cellular response and the capacity for transplantation after lowering the pH to 6.5, below pKb. A direct relationship of the DPAEMA functionalization degree on the detachment efficiency was observed, since the hydrogels with the highest molar load of DPAEMA showed higher mitochondrial metabolic activity after cell detachment.

Bioabsorbable Composites Based on Polymeric Matrix (PLA and PCL) Reinforced with Magnesium (Mg) for Use in Bone Regeneration Therapy: Physicochemical Properties and Biological Evaluation

Improvements in Tissue Engineering and Regenerative Medicine (TERM)-type technologies have allowed the development of specific materials that, together with a better understanding of bone tissue structure, have provided new pathways to obtain biomaterials for bone tissue regeneration. In this manuscript, bioabsorbable materials are presented as emerging materials in tissue engineering therapies related to bone lesions because of their ability to degrade in physiological environments while the regeneration process is completed. This comprehensive review aims to explore the studies, published since its inception (2010s) to the present, on bioabsorbable composite materials based on PLA and PCL polymeric matrix reinforced with Mg, which is also bioabsorbable and has recognized osteoinductive capacity. The research collected in the literature reveals studies based on different manufacturing and dispersion processes of the reinforcement as well as the physicochemical analysis and corresponding biological evaluation to know the osteoinductive capacity of the proposed PLA/Mg and PCL/Mg composites. In short, this review shows the potential of these composite materials and serves as a guide for those interested in bioabsorbable materials applied in bone tissue engineering.

Composing On-Program Triggers and On-Demand Stimuli into Biosensor Drug Carriers in Drug Delivery Systems for Programmable Arthritis Therapy

Medication in arthritis therapies is complex because the inflammatory progression of rheumatoid arthritis (RA) and osteoarthritis (OA) is intertwined and influenced by one another. To address this problem, drug delivery systems (DDS) are composed of four independent exogenous triggers and four dependent endogenous stimuli that are controlled on program and induced on demand, respectively. However, the relationships between the mechanisms of endogenous stimuli and exogenous triggers with pathological alterations remain unclear, which results in a major obstacle in terms of clinical translation. Thus, the rationale for designing a guidance system for these mechanisms via their key irritant biosensors is in high demand. Many approaches have been applied, although successful clinical translations are still rare. Through this review, the status quo in historical development is highlighted in order to discuss the unsolved clinical difficulties such as infiltration, efficacy, drug clearance, and target localisation. Herein, we summarise and discuss the rational compositions of exogenous triggers and endogenous stimuli for programmable therapy. This advanced active pharmaceutical ingredient (API) implanted dose allows for several releases by remote controls for endogenous stimuli during lesion infections. This solves the multiple implantation and local toxic accumulation problems by using these flexible desired releases at the specified sites for arthritis therapies.