Cell-Material Interplay in Focal Adhesion Points

Hydroxyapatite microspheres encapsulated within hybrid hydrogel promote skin regeneration through the activation of Calcium Signaling and Motor Protein pathway

Hydroxyapatite (HAp), traditionally recognized for its efficacy in bone regeneration, has rarely been explored for skin regeneration applications. This investigation explored HAp microspheres with distinct physicochemical properties tailored away from conventional bone regeneration parameters, and the capacity promoting skin regeneration and mitigating the aging process were investigated when encapsulated in hyaluronate hydrogels. By benchmarking against well-established dermal fillers like PMMA and PLLA, it was revealed the specific attributes of HAp that were conducive to skin regeneration, providing initial insights into the underlying mechanism. HAp enhanced the fibroblast functionality by triggering minimal adaptive immune responses and enhancing the Calcium Signaling and Motor Protein Signaling pathways. This modulation supported the production of normal collagen fibers, essential for ECM maturation and skin structural integrity. The significant ECM regeneration and remodeling capabilities exhibited by the HAp-encapsulated hybrid hydrogels suggested promising application in facial rejuvenation procedures, potentially making a breakthrough in aesthetic and reconstructive surgery.

Modulating cell adhesion and infiltration in advanced scaffold designs based on PLLA fibers with rGO and MXene (Ti3C2T x )

The development of electrospun scaffolds that support cell adhesion and infiltration remains a critical challenge in tissue engineering. In this study, we investigate the influence of two-dimensional (2D) fillers-reduced graphene oxide (rGO) and MXene (Ti3C2T x )-incorporated into poly(L-lactic acid) (PLLA) electrospun fibers on their properties and osteoblast responses. The presence of fillers modified fiber arrangement and created varying inter-fiber spacing due to surface charge repulsion and agglomeration. Importantly, surface potential measurements via Kelvin probe force microscopy (KPFM) of PLLA fibers show a significant shift caused by the incorporation of Ti3C2T x to ∼400 mV compared to ∼50 mV for rGO. In vitro tests indicate that rGO-modified scaffolds support osteoblast infiltration up to ∼100 μm, unlike PLLA fibers, which limit cell infiltration to a maximum of ∼70 μm. However, Ti3C2T x promotes even deeper (∼120 μm) and more uniform cell's infiltration due to changes in scaffold architecture. High-resolution confocal imaging confirmed that PLLA-Ti3C2T x fosters larger, elongated adhesion site clusters of cells, whereas rGO increases cell's adhesion site density in relation to PLLA scaffolds without any filler. Our findings highlight the distinct roles of rGO and Ti3C2T x in modulating scaffold geometry, mechanical behavior, and cellular interactions. Tailoring the composition and distribution of conductive fillers in fibers offers a promising strategy for optimizing scaffold performance in tissue engineering applications.

Tetrahedral DNA Nanostructure-Modified Nanocoating for Improved Bioaffinity and Osseointegration of Titanium

Titanium (Ti) is extensively used in the medical field because of its excellent biomechanical properties; however, how to precisely fabricate Ti surfaces at a nanoscale remains challenging. In this study, a DNA nanocoating system to functionalize Ti surfaces via a series of sequential reactions involving hydroxylation, silanization, and click chemistry is developed. Tetrahedral DNA nanostructures (TDNs) of two different sizes (≈7 and 30 nm) are assembled and characterized for subsequent surface attachment. In vitro and in vivo assays demonstrated significantly enhanced cell adhesion, spreading, proliferation, osteogenesis, and osseointegration on Ti surfaces modified with 30-nm TDNs, compared to slightly improved effects with 7-nm TDNs. Mechanistic studies showed that the focal adhesion pathway contributed to the enhanced bioaffinity of the 30-nm TDNs, as evidenced by the upregulated expression of vinculin and activation of the Akt signaling pathway. Moreover, under inflammatory or hypoxic conditions, Ti surfaces modified with 30-nm TDNs maintained excellent cellular performance comparable to that under normal conditions, suggesting a broader adaptability for DNA nanoparticles. Thus, better performance is achieved following modification with 30-nm TDNs. In summary, the proposed DNA-guided nanocoating system provides a novel and efficient strategy for the surface nanofabrication of Ti.

Interfacial blending in co-axially electrospun polymer core-shell fibers and their interaction with cells via focal adhesion point analysis

Electrospun polymer scaffolds have gained prominence in biomedical applications, including tissue engineering, drug delivery, and wound dressings, due to their customizable properties. As the interplay between cells and materials assumes fundamental significance in biomaterials research, understanding the relationship between fiber properties and cell behaviour is imperative. Nevertheless, altering fiber properties introduces complexity by intertwining mechanical and surface chemistry effects, challenging the differentiation of their individual impacts on cell behaviour. Core-shell fibers present an appealing solution, enabling the control of mechanical properties of scaffolds, flexibility in material and drug selection, efficient encapsulation, strong protection of bioactive drugs against harsh environments, and controlled, prolonged drug release. This study addresses a key challenge in core-shell fiber design related to the blending effect between core and shell polymers. Two types of fibers, PMMA and core-shell PC-PMMA, were electrospun, and thorough analyses confirmed the desired core-shell structure in PC-PMMA fibers. Surface chemistry analysis revealed PC diffusion to the PMMA shell of the core-shell fiber during electrospinning, subsequently prompting an investigation of the fiber's surface potential. Conducting cellular studies on osteoblasts by super-resolution confocal microscopy provided insights into the direct influence of interfacial polymer blending and, consequently, altered fiber surface and mechanical properties on cell focal adhesion points, bridging the gap between material attributes and cell responses in core-shell fibers.