Immune Response Testing of Electrospun Polymers: An Important Consideration in the Evaluation of Biomaterials

Due primarily to cell sourcing issues, many in the field of tissue engineering have opted to create scaffolds that promote in situ regeneration, using the body as both the bioreactor and the cell source for the remodeling of scaffolds, resulting in the formation of native tissue. This practice raises many concerns, with the body’s immune response to such an implant often being neglected as a potential problem in preliminary design and biocompatibility testing. More importantly, what happens over time in terms of the immune responses as the biodegradable scaffold structures being utilized to promote in situ regeneration begin to degrade, forming structural fragments and degradation products? In summary, immune response evaluations are critical considerations that must be conducted when evaluating bioresorbable scaffolds. In addition, it is essential that these evaluations analyze materials for their potential dose-response and time-course effects on the various components of innate and acquired immunity

A comparative study of polyurethane nanofibers with different patterns and its analogous nanofibers containing MWCNTs

Tissue engineering is a multidisciplinary field that has evolved in various dimensions in recent years. One of the main aspects in this field is the proper adjustment and final compatibility of implants at the target site of surgery. For this purpose, it is desired to have the materials fabricated at the nanometer scale, since these dimensions will ultimately accelerate the fixation of implants at the cellular level. In this study, electrospun polyurethane nanofibers and their analogous nanofibers containing MWCNTs are introduced for tissue engineering applications. Since MWCNTs agglomerate to form bundles, a high intensity sonication procedure was used to disperse them, followed by electrospinning the polymer solutions that contained these previously dispersed MWCNTs. Characterization of the produced nanofibers has confirmed production of different non-woven mats, which include random, semi-aligned and mostly aligned patterns. A simultaneous and comparative study was conducted on the nanofibers with respect to their thermal stability, mechanical properties and biocompatibility. Results indicate that the mostly aligned nanofibers pattern presents higher thermal stability, mechanical properties, and biocompatibility. Furthermore, incorporation of MWCNTs among the different arrangements significantly improved the mechanical properties and cell alignment along the nanofibers

Electrospun Collagen: A Tissue Engineering Scaffold with Unique Functional Properties in a Wide Variety of Applications

Type I collagen and gelatin, a derivative of Type I collagen that has been denatured, can each be electrospun into tissue engineering scaffolds composed of nano- to micron-scale diameter fibers. We characterize the biological activity of these materials in a variety of tissue engineering applications, including endothelial cell-scaffold interactions, the onset of bone mineralization, dermal reconstruction, and the fabrication of skeletal muscle prosthetics. Electrospun collgen (esC) consistently exhibited unique biological properties in these functional assays. Even though gelatin can be spun into fibrillar scaffolds that resemble scaffolds of esC, our assays reveal that electrospun gelatin (esG) lacks intact α chains and is composed of proinflammatory peptide fragments. In contrast, esC retains intact α chains and is enriched in the α 2(I) subunit. The distinct fundamental properties of the constituent subunits that make up esC and esG appear to define their biological and functional properties

Electrospun Fibrinogen-Polydioxanone Composite Matrix: Potential for In Situ Urologic Tissue Engineering

Our objective is to demonstrate an electrospun fibrinogen-PDO (polydioxanone) composite scaffold will retain the superior cellular interaction of fibrinogen while producing a product with the functional strength needed for direct implantation. Fibrinogen-PDO composite scaffolds were electrospun with PDO ratios of 0% (pure fibrinogen), 10%, 20%, 30%, 40%, 50% and 100% (pure PDO) and disinfected using standard methods. Scaffolds were seeded with human BSM (bladder smooth muscle cells) and incubated with twice weekly media changes. Samples were removed at 7, 14 and 21 days for evaluation by collagen assay, scanning electron microscopy and histology. Cell seeding and culture demonstrated human BSM readily migrate throughout and remodel electrospun fibrinogen-PDO composite scaffolds with deposition of native collagen. Cell migration and collagen deposition increased with increasing fibrinogen concentration while scaffold integrity increased with increasing PDO concentration. Electrospun fibrinogen-PDO composite structures promote rapid cellular in-growth by human BSM while maintaining structural integrity. The fibrinogen to PDO ratio can be adjusted to achieve the desired properties required for a specific tissue engineering application. Our ultimate objective is to utilize this innovative biomaterial technology to produce an acellular, bioresorbable product that enables in situ tissue regeneration. While there is still much work to be done, these initial findings indicate fibrinogen-PDO composite scaffolds deserve further investigation

A Preliminary Study on the Potential of Manuka Honey and Platelet-Rich Plasma in Wound Healing

Aim. The purpose of this study was to determine the in vitro response of cells critical to the wound healing process in culture media supplemented with a lyophilized preparation rich in growth factors (PRGF) and Manuka honey. Materials and Methods. This study utilized cell culture media supplemented with PRGF, as well as whole Manuka honey and the medical-grade Medihoney (MH), a Manuka honey product. The response of human fibroblasts (hDF), macrophages, and endothelial cells (hPMEC) was evaluated, with respect to cell proliferation, chemotaxis, collagen matrix production, and angiogenic potential, when subjected to culture with media containing PRGF, MH, Manuka honey, and a combination of PRGF and MH. Results. All three cell types demonstrated increases in cellular activity in the presence of PRGF, with further increases in activity seen in the presence of PRGF+MH. hDFs proved to be the most positively responsive cells, as they experienced enhanced proliferation, collagen matrix production, and migration into an in vitro wound healing model with the PRGF+MH-supplemented media. Conclusion. This preliminary in vitro study is the first to evaluate the combination of PRGF and Manuka honey, two products with the potential to increase regeneration individually, as a combined product to enhance dermal regeneration

A Preliminary Study on the Potential of Manuka Honey and Platelet-Rich Plasma in Wound Healing

Aim. The purpose of this study was to determine the in vitro response of cells critical to the wound healing process in culture media supplemented with a lyophilized preparation rich in growth factors (PRGF) and Manuka honey. Materials and Methods. This study utilized cell culture media supplemented with PRGF, as well as whole Manuka honey and the medical-grade Medihoney (MH), a Manuka honey product. The response of human fibroblasts (hDF), macrophages, and endothelial cells (hPMEC) was evaluated, with respect to cell proliferation, chemotaxis, collagen matrix production, and angiogenic potential, when subjected to culture with media containing PRGF, MH, Manuka honey, and a combination of PRGF and MH. Results. All three cell types demonstrated increases in cellular activity in the presence of PRGF, with further increases in activity seen in the presence of PRGF+MH. hDFs proved to be the most positively responsive cells, as they experienced enhanced proliferation, collagen matrix production, and migration into an in vitro wound healing model with the PRGF+MH-supplemented media. Conclusion. This preliminary in vitro study is the first to evaluate the combination of PRGF and Manuka honey, two products with the potential to increase regeneration individually, as a combined product to enhance dermal regeneration

Modeling Early Stage Bone Regeneration With Biomimetic Electrospun Fibrinogen Nanofibers and Adipose-Derived Mesenchymal Stem Cells

The key events of the earliest stages of bone regeneration have been described in vivo although not yet modeled in an in vitro environment, where mechanistic cell-matrix-growth factor interactions can be more effectively studied. Here, we explore an early-stage bone regeneration model where the ability of electrospun fibrinogen (Fg) nanofibers to regulate osteoblastogenesis between distinct mesenchymal stem cells populations is assessed. Electrospun scaffolds of Fg, polydioxanone (PDO), and a Fg:PDO blend were seeded with adipose-derived mesenchymal stem cells (ASCs) and grown for 7-21 days in osteogenic differentiation media or control growth media. Scaffolds were analyzed weekly for histologic and molecular evidence of osteoblastogenesis. In response to osteogenic differentiation media, ASCs seeded on the Fg scaffolds exhibit elevated expression of multiple genes associated with osteoblastogenesis. Histologic stains and scanning electron microscopy demonstrate widespread mineralization within the scaffolds, as well as de novo type I collagen synthesis. Our data demonstrates that electrospun Fg nanofibers support ASC osteogenic differentiation, yet the scaffold itself does not appear to be osteoinductive. Together, ASCs and Fg recapitulate early stages of bone regeneration ex vivo and presents a prospective autologous therapeutic approach for bone repair

Imaging, Spectroscopy, Mechanical, Alignment and Biocompatibility Studies of Electrospun Medical Grade Polyurethane (Carbothane™ 3575A) Nanofibers and Composite Nanofibers Containing Multiwalled Carbon Nanotubes

In the present study, we discuss the electrospinning of medical grade polyurethane (Carbothane™ 3575A) nanofibers containing multi-walled-carbon-nanotubes (MWCNTs). A simple method that does not depend on additional foreign chemicals has been employed to disperse MWCNTs through high intensity sonication. Typically, a polymer solution consisting of polymer/MWCNTs has been electrospun to form nanofibers. Physiochemical aspects of prepared nanofibers were evaluated by SEM, TEM, FT-IR and Raman spectroscopy, confirming nanofibers containing MWCNTs. The biocompatibility and cell attachment of the produced nanofiber mats were investigated while culturing them in the presence of NIH 3T3 fibroblasts. The results from these tests indicated non-toxic behavior of the prepared nanofiber mats and had a significant attachment of cells towards nanofibers. The incorporation of MWCNTs into polymeric nanofibers led to an improvement in tensile stress from 11.40 ± 0.9 to 51.25 ± 5.5 MPa. Furthermore, complete alignment of the nanofibers resulted in an enhancement on tensile stress to 72.78 ± 5.5 MPa. Displaying these attributes of high mechanical properties and non-toxic nature of nanofibers are recommended for an ideal candidate for future tendon and ligament grafts

Imaging, Spectroscopic, Mechanical and Biocompatibility Studies of Electrospun Tecoflex® EG 80A Nanofibers and Composites Thereof Containing Multiwalled Carbon Nanotubes

The present study discusses the design, development and characterization of electrospun Tecoflex® EG 80A class of polyurethane nanofibers and the incorporation of multiwalled carbon nanotubes (MWCNTs) to these materials. Scanning electron microscopy results confirmed the presence of polymer nanofibers, which showed a decrease in fiber diameter at 0.5% wt. and 1% wt. MWCNTs loadings, while transmission electron microscopy showed evidence of the MWCNTs embedded within the polymer matrix. The fourier transform infrared spectroscopy and Raman spectroscopy were used to elucidate the polymer-MWCNTs intermolecular interactions, indicating that the C-N and N-H bonds in polyurethanes are responsible for the interactions with MWCNTs. Furthermore, tensile testing indicated an increase in the Young’s modulus of the nanofibers as the MWCNTs concentration was increased. Finally, NIH 3T3 fibroblasts were seeded on the obtained nanofibers, demonstrating cell biocompatibility and proliferation. Therefore, the results indicate the successful formation of polyurethane nanofibers with enhanced mechanical properties, and demonstrate their biocompatibility, suggesting their potential application in biomedical area

A Preliminary Study on the Potential of Manuka Honey and Platelet-Rich Plasma in Wound Healing

Aim. The purpose of this study was to determine the in vitro response of cells critical to the wound healing process in culture media supplemented with a lyophilized preparation rich in growth factors (PRGF) and Manuka honey. Materials and Methods. This study utilized cell culture media supplemented with PRGF, as well as whole Manuka honey and the medical-grade Medihoney (MH), a Manuka honey product. The response of human fibroblasts (hDF), macrophages, and endothelial cells (hPMEC) was evaluated, with respect to cell proliferation, chemotaxis, collagen matrix production, and angiogenic potential, when subjected to culture with media containing PRGF, MH, Manuka honey, and a combination of PRGF and MH. Results. All three cell types demonstrated increases in cellular activity in the presence of PRGF, with further increases in activity seen in the presence of PRGF+MH. hDFs proved to be the most positively responsive cells, as they experienced enhanced proliferation, collagen matrix production, and migration into an in vitro wound healing model with the PRGF+MH-supplemented media. Conclusion. This preliminary in vitro study is the first to evaluate the combination of PRGF and Manuka honey, two products with the potential to increase regeneration individually, as a combined product to enhance dermal regeneration