Electrophoretic Deposition of 58S Bioactive Glass- Polymer Composite Coatings on 316L Stainless Steel: An Optimization for Corrosion, Bioactivity, and Cytocompatibility.

This study presents a facile fabrication of 58S bioactive glass (BG)-polymer composite coatings on a 316L stainless steel (SS) substrate using the electrophoretic deposition technique. The suspension characteristics and deposition kinetics of BG, along with three different polymers, namely ethylcellulose (EC), poly(acrylic acid) (PAA), and polyvinylpyrrolidone (PVP), have been utilized to fabricate the coatings. Among all coatings, 58S BG and EC polymers are selected as the final composite coating (EC6) owing to their homogeneity and good adhesion. EC6 coating exhibits a thickness of ∼18 µm and an average roughness of ∼2.5 µm. Herein, EC6 demonstrates better hydroxyapatite formation compared to PAA and PVP coatings in simulated body fluid-based mineralization studies for a period of 28 days. Corrosion studies of EC6 in phosphate-buffered saline further confirm the higher corrosion resistance properties after 14 days. In vitro cytocompatibility studies using human placental mesenchymal stem cells demonstrate an increase in cellular viability, attachment, and higher proliferation compared to the bare SS substrate. EC6 coatings promote osteogenic differentiation, which is confirmed via the upregulation of the OPN and OCN genes. Moreover, the EC6 sample exhibits improved antibacterial properties against Escherichia coli and Staphylococcus aureus compared to the uncoated ones. The findings of this work emphasize the potential of electrophoretically fabricated BG-EC composite coatings on SS substrates for orthopedic applications.

Biochemical and immunomodulatory insights of extracellular matrix from decellularized human whole cervix: recellularization andin vivoECM remodeling interplay.

Extracellular matrix (ECM) rich whole organ bio-scaffolds, preserving structural integrity and essential growth factors, has potential towards regeneration and reconstruction. Women with cervical anomalies or trauma can benefit from clinical cervicovaginal repair using constructs rich in site specific ECM. In this study, complete human cervix decellularization was achieved using a modified perfusion-based stir bench top decellularization method. This was followed by physico-chemical processes including perfusion of ionic agents, enzymatic treatment and washing using detergent solutions for a duration of 10-12 d. Histopathological analysis, as well as DNA quantification confirmed the efficacy of the decellularization process. Tissue ultrastructure integrity was preserved and the same was validated via scanning electron microscopy and transmission electron microscopy studies. Biochemical analysis and structural characterizations like Fourier transform infrared, Raman spectroscopy of decellularized tissues demonstrated preservation of important proteins, crucial growth factors, collagen, and glycosaminoglycans.In vitrostudies, using THP-1 and human umbilical vein endothelial cell (HUVEC) cells, demonstrated macrophage polarization from M1 to M2 and vascular functional genes enhancement, respectively, when treated with decellularized human cervical matrix (DHCp). Crosslinked DHC scaffolds were recellularized with site specific human cervical epithelial cells and HUVEC, showing non-cytotoxic cell viability and enhanced proliferation. Furthermore, DHC scaffolds showed immunomodulatory effectsin vivoon small rodent model via upregulation of M2 macrophage genes as compared to decellularized rat cervix matrix scaffolds (DRC). DHC scaffolds underwent neo-vascularization followed by ECM remodeling with enhanced tissue integration.

Biodegradable Multi-layered Silk Fibroin-PCL Stent for the Management of Cervical Atresia: In Vitro Cytocompatibility and Extracellular Matrix Remodeling In Vivo.

Cervical atresia is a rare congenital Müllerian duct anomaly that manifests as the absence or deformed nonfunctional presence of the cervix. Herein, a multi-layered biodegradable stent is fabricated using a homogeneous blend of silk fibroin with polycaprolactone using hexafluoroisopropanol as a common solution. Briefly, a concentric cylinder of 3D honeycomb layer is sandwiched within electrospun sheets for fixing at the cervico-uterine junction to pave the way of cervical reconstruction. An average length of 40 mm with 3 mm diameter is fabricated for the hybrid stent design. SEM evidences an evenly distributed pore architecture of the electrospun layer, and mechanical characterization of stent reveals a tensile strength of 1.7 ± 0.2 MPa, with a Young's modulus of 5.9 ± 0.1 MPa. Physico-chemical characterization confirms the presence of silk fibroin and poly caprolactone within the engineered stent. Following 14 days of pepsin enzymatic degradation, 18% degradation and a contact angle measurement of 97° are observed. In vitro cytocompatibility studies are performed using site-specific primary human cervical squamous, columnar epithelial cells, and human endometrial stromal cells. The study demonstrates non-cytotoxic cells' viability (no significant toxicity), improved cell anchoring, adherence among the stent layers, and proliferation in the 3D microenvironment. Furthermore, in vivo subcutaneous studies in the rodent model indicate that the implanted stent undergoes constructive remodeling, neo-tissue creation, neo-vasculature formation, and re-epithelialization while maintaining patency for 2 months.

Human placenta/umbilical cord derivatives in regenerative medicine - Prospects and challenges.

The human placenta and umbilical cord, natural birth biowaste, are a housing unit for numerous bioactive macromolecules, growth factors, collagen and GAGs, with an array of high-quality stem cells. MSCs isolated from the human placenta and umbilical cord are utilized in both research and medical applications due to their sustainable sourcing, high viability, multipotent lineage and potency. They present an unprecedented opportunity in the tissue engineering, biomedical and biotechnology fields with minimal ethical constraints and nominal cost. Considering the world population and daily birth rates, with appropriate utilization and management, they could resolve the MSC shortage in the global stem cell therapy market and present biomedical waste disposal. A considerable number of clinical trials are presently underway where placenta-derived stem cells have been administered for different pathologies. Since the umbilical cord and placenta's primary function is to sustain the fetus until delivery, it has an ample supply of nutrients, proteins and essential factors necessary to assist cell viability and proliferation. Present research and medical applications include the fabrication of ECM-based nanofibers, disease models, micro-tissue, hybrid models and artificial implants. Future utilization of birthing biomedical waste in medical engineering and research will provide a rich and sustainable source of stem cells and extracellular matrix for enhanced biocompatibility and regeneration.

High fibroin-loaded silk-PCL electrospun fiber with core-shell morphology promotes epithelialization with accelerated wound healing.

Silk fibroin (SF) is a widely explored biopolymer for wound-healing applications due to the presence of amino acids in the biodegradable polymer chain with superior mechanical properties. Herein, a high SF-loaded fibrous matrix along with poly(ε-caprolactone) (PCL) was fabricated using electrospinning of emulsion and blend compositions to modulate nanostructure morphology. A comparative study of the physicomechanical properties of electrospun fibers with emulsion (eS7P3) and homogenous blend (bS7P3) was performed as well. In both compositions, SF loading of up to 70% was successfully achieved in the spun fibers while emulsion yielded core-shell morphology, and the blend resulted in monolith fiber architecture as evidenced by TEM microscopy. Further characterization revealed superior mechanical properties in S7P3 fiber with core-shell morphology, as compared to those in the monolith in terms of a higher degree of crystallinity with Young's modulus of 60 MPa under tensile test and nanoindentation modulus of 1.59 ± 0.8 GPa. Further, eS7P3 nanostructure morphology containing silk in the core with a thin outer layer of PCL facilitated relatively faster biodegradation in the lysozyme medium, as compared to that in the monolith. Owing to the presence of a hydrophobic shell, protein adsorption on the fibrous mat presented slow but steady kinetics up to 24 h. When the scaffold was seeded with human placenta-derived mesenchymal stem cells (hPMSCs), in vitro study confirmed that the eS7P3 structure had marginally higher cell proliferation with superior cell infiltration than the monolith. Further, in vivo study involving a rodent model showed the potential of the eS7P3 fiber substrate with a core-shell structure for accelerating full-thickness wound healing by inducing hair follicle and wound closure with less scar formation after 15 days.

Role of nanofibers on MSCs fate: Influence of fiber morphologies, compositions and external stimuli.

In regenerative medicine, self-regulated tissue regeneration is perceived by Mesenchymal Stem Cells (MSCs) fate due to their tissue-specific differentiation, which is an emerging yet promising tool for therapeutics. MSCs with their innate nature like secretion of bioactive molecules, multilineage differentiation and proliferation supported tissue repair. MSCs interact with extracellular matrix (ECM) components like collagen, glycosaminoglycans (GAGs), proteoglycans and various proteins that are present in the form of nanofibers representing variable matrix elasticity along with topographies and bioactive cues. Synthetic nanofibers also showed to mimic native tissue microenvironment and supported regeneration owing to structural resemblance with ECM for anchorage-dependent cells. Different nanofibers generated using various polymer precursors and their resultant scaffolds, architectures, compositions etc. were studied for their influence on MSCs activities to improvise cell-cell and cell-material interactions. Electrospinning, popular nanotechnology for fiber formation based on electrohydrodynamic theory, is widely used for many applications due to its simplicity, efficacy and environmentally friendliness. Electrospun nanofibers were extensively investigated to understand the influence of material towards manipulating stem cells based on regenerative medicine. Subsequently, the influence of different solutions and process parameters were studied for nanofiber structure repeatability and emphasized on fiber properties such as diameter, mechanical properties, degradation rate, and porosity. Recent approaches towards scale-up for nanofiber production by electrospinning and other novel techniques are also presented briefly. The fate of MSCs, while seeded on nanofibers under external stimuli viz. electrical, mechanical, magnetic and electromagnetic field, is reviewed to find the niche for differentiation pathways. Further, several external stimuli presented as important factors motivating cellular differentiation in combination with specific conditions without the use of any chemical cues.