In vivo acute and humoral response to three-dimensional porous soy protein scaffolds

Porosity controlled soya protein isolate-polyethylene oxide multifunctional dual membranes as smart wound dressings

Multifunctional membranes S7P0.7, S7P3.0, and dual membranes composed of soya protein isolate (SPI) and polyethylene oxide (PEO) were produced for wound dressing applications. The internal structure of the membranes was confirmed by scanning electron microscopy (SEM) to be homogeneous and coarser with a porous-like network. S7P3.0 showed the tensile strength of 0.78 ± 0.04 MPa. In the absence of antibiotics, the dual membrane (combination of S7P0.7 and S7P3.0) exhibited potential antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. Hemolysis quantitative data presented in the image demonstrates that all samples exhibited hemolysis levels below 5 %. Dual membrane showed 77.93 ± 9.5 % blood uptake which reflects its absorption capacity. The combination of S7P0.7 and S7P3.0 influenced the dual membrane's antibacterial, biocompatibility, and good hemolytic potentials. The dual membranes' promising histology features after implantation suggest they could be used as wound dressings.

Towards a More Realistic In Vitro Meat: The Cross Talk between Adipose and Muscle Cells

According to statistics and future predictions, meat consumption will increase in the coming years. Considering both the environmental impact of intensive livestock farming and the importance of protecting animal welfare, the necessity of finding alternative strategies to satisfy the growing meat demand is compelling. Biotechnologies are responding to this demand by developing new strategies for producing meat in vitro. The manufacturing of cultured meat has faced criticism concerning, above all, the practical issues of culturing together different cell types typical of meat that are partly responsible for meat’s organoleptic characteristics. Indeed, the existence of a cross talk between adipose and muscle cells has critical effects on the outcome of the co-culture, leading to a general inhibition of myogenesis in favor of adipogenic differentiation. This review aims to clarify the main mechanisms and the key molecules involved in this cross talk and provide an overview of the most recent and successful meat culture 3D strategies for overcoming this challenge, focusing on the approaches based on farm-animal-derived cells.

Protein scaffolds in human clinics

Fundamental clinical areas such as drug delivery and regenerative medicine require biocompatible materials as mechanically stable scaffolds or as nanoscale drug carriers. Among the wide set of emerging biomaterials, polypeptides offer enticing properties over alternative polymers, including full biocompatibility, biodegradability, precise interactivity, structural stability and conformational and functional versatility, all of them tunable by conventional protein engineering. However, proteins from non-human sources elicit immunotoxicities that might bottleneck further development and narrow their clinical applicability. In this context, selecting human proteins or developing humanized protein versions as building blocks is a strict demand to design non-immunogenic protein materials. We review here the expanding catalogue of human or humanized proteins tailored to execute different levels of scaffolding functions and how they can be engineered as self-assembling materials in form of oligomers, polymers or complex networks. In particular, we emphasize those that are under clinical development, revising their fields of applicability and how they have been adapted to offer, apart from mere mechanical support, highly refined functions and precise molecular interactions.

Antibacterial and antioxidant activity of cinnamon essential oil-laden 45S5 bioactive glass/soy protein composite scaffolds for the treatment of bone infections and oxidative stress

This study aimed to fabricate cinnamon essential oil (CO)-laden 45S5 bioactive glass (BG)/soy protein (SP) scaffolds exhibiting antioxidant and antibacterial activity. In this regard, 45S5 BG-based scaffolds were produced by the foam replica method, and subsequently the scaffolds were coated with various concentrations of CO (2.5, 5 and 7 (v/v) %) incorporated SP solution. Scanning electron microscopy images revealed that the CO-laden SP effectively attached to the 45S5 BG scaffold struts. The presence of 45S5 BG, SP and CO was confirmed using Fourier transform infrared spectroscopy. Compressive strength results indicated that SP based coatings improved the scaffolds' mechanical properties compared to uncoated BG scaffolds. The loading efficiency and releasing behaviour of the different CO concentrations were tested by gas chromatography-mass spectroscopy and UV-Vis spectroscopy. The results showed that CO incorporated scaffolds have controlled releasing behaviour over seven days. Furthermore, the coating on the scaffold surfaces slightly retarded, but it did not inhibit, the in vitro bioactivity of the scaffolds. Moreover, the antioxidant and antibacterial activity of CO was studied. The free radical scavenging activity measured by DPPH was 5 ± 1, 41 ± 3, 44 ± 1 and 43 ± 1 % for BGSP, CO2.5, CO5 and CO7, respectively. The antioxidant activity was thus enhanced by incorporating CO. Agar diffusion and colony counting results indicated that the incorporation of CO increased the antibacterial activity of scaffolds against S. aureus and E. coli. In addition, cytotoxicity of the scaffolds was investigated using MG-63 osteoblast-like cells. The results showed that the BG-SP scaffold was non-toxic under the investigated conditions, whereas dose-dependent toxicity was observed in CO-laden scaffolds. Considered together, the developed phytotherapeutic agent laden 45S5 BG-based scaffolds are promising for bone tissue engineering exhibiting capability to combat bone infections and to protect against oxidative stress damage.

Review of Low-Cost 3D Bioprinters: State of the Market and Observed Future Trends

Three-dimensional (3D) bioprinting has become mainstream for precise and repeatable high-throughput fabrication of complex cell cultures and tissue constructs in drug testing and regenerative medicine, food products, dental and medical implants, biosensors, and so forth. Due to this tremendous growth in demand, an overwhelming amount of hardware manufacturers have recently flooded the market with different types of low-cost bioprinter models-a price segment that is most affordable to typical-sized laboratories. These machines range in sophistication, type of the underlying printing technology, and possible add-ons/features, which makes the selection process rather daunting (especially for a nonexpert customer). Yet, the review articles available in the literature mostly focus on the technical aspects of the printer technologies under development, as opposed to explaining the differences in what is already on the market. In contrast, this paper provides a snapshot of the fast-evolving low-cost bioprinter niche, as well as reputation profiles (relevant to delivery time, part quality, adherence to specifications, warranty, maintenance, etc.) of the companies selling these machines. Specifically, models spanning three dominant technologies-microextrusion, droplet-based/inkjet, and light-based/crosslinking-are reviewed. Additionally, representative examples of high-end competitors (including up-and-coming microfluidics-based bioprinters) are discussed to highlight their major differences and advantages relative to the low-cost models. Finally, forecasts are made based on the trends observed during this survey, as to the anticipated trickling down of the high-end technologies to the low-cost printers. Overall, this paper provides insight for guiding buyers on a limited budget toward making informed purchasing decisions in this fast-paced market.

3D Bioprinting of Functional Skin Substitutes: From Current Achievements to Future Goals

The aim of this review is to present 3D bioprinting of skin substitutes as an efficient approach of managing skin injuries. From a clinical point of view, classic treatments only provide physical protection from the environment, and existing engineered scaffolds, albeit acting as a physical support for cells, fail to overcome needs, such as neovascularisation. In the present work, the basic principles of bioprinting, together with the most popular approaches and choices of biomaterials for 3D-printed skin construct production, are explained, as well as the main advantages over other production methods. Moreover, the development of this technology is described in a chronological manner through examples of relevant experimental work in the last two decades: from the pioneers Lee et al. to the latest advances and different innovative strategies carried out lately to overcome the well-known challenges in tissue engineering of skin. In general, this technology has a huge potential to offer, although a multidisciplinary effort is required to optimise designs, biomaterials and production processes.

Recent Advances in 3D Printing with Protein-Based Inks

Three-dimensional (3D) printing is a transformative manufacturing strategy, allowing rapid prototyping, customization, and flexible manipulation of structure-property relationships. Proteins are particularly appealing to formulate inks for 3D printing as they serve as essential structural components of living systems, provide a support presence in and around cells and for tissue functions, and also provide the basis for many essential ex vivo secreted structures in nature. Protein-based inks are beneficial in vivo due to their mechanics, chemical and physical match to the specific tissue, and full degradability, while also to promoting implant-host integration and serving as an interface between technology and biology. Exploiting the biological, chemical, and physical features of protein-based inks can provide key opportunities to meet the needs of tissue engineering and regenerative medicine. Despite these benefits, protein-based inks impose nontrivial challenges to 3D printing such as concentration and rheological features and reconstitution of the structural hierarchy observed in nature that is a source of the robust mechanics and functions of these materials. This review introduces photo-crosslinking mechanisms and rheological principles that underpins a variety of 3D printing techniques. The review also highlights recent advances in the design, development, and biomedical utility of monolithic and composite inks from a range of proteins, including collagen, silk, fibrinogen, and others. One particular focus throughout the review is to introduce unique material characteristics of proteins, including amino acid sequences, molecular assembly, and secondary conformations, which are useful for designing printing inks and for controlling the printed structures. Future perspectives of 3D printing with protein-based inks are also provided to support the promising spectrum of biomedical research accessible to these materials.

4D printing of products based on soy protein isolate via microwave heating for flavor development

The aim of this study is to establish food 4D printing products with the property of automatic flavor change by the post-printing application of microwave as an external thermal stimulus. The combination of a formulation comprised of soybean protein isolate (SPI), k-carrageenan (CAR) and vanilla flavor (VNL) was used as printing material. The change in flavor profile was observed by the level of external heat stimulus as a 4D effect. The results of e-nose revealed a significant difference (P < 0.05) in sensors 2, 5, 6, 9, 10, 12 and 13 in the sample added with vanilla flavor meanwhile GC-MS detected 25 volatiles compounds. Notably, four new generated flavor compounds (1-Octen-3-ol, Maltol, Ethyl maltol and eugenal) were identified when added with vanilla flavor. Moreover, e-tongue results indicated the taste characteristics of the sample with vanilla flavor presenting more intense bitterness, astringency, umami, richness and saltiness. The rheological property and water distribution (LF-NMR) determined at different concentrations levels of carrageenan showed that SPI gel made with 3% (w/v) carrageenan was the most suitable for 3D printing among all three concentrations considered in this study. Overall, the results can conclude that the addition of carrageenan and post-printing microwave heating at an optimum level of microwave power enhanced the printability and flavor of SPI gel.

Autologous cell membrane coatings on tissue engineering xenografts for suppression and alleviation of acute host immune responses

Xenogeneic extracellular matrix (ECM) based tissue engineering graft is one of the most promising products for transplantation therapies, which could alleviate the pain of patients and reduce surgery cost. However, in order to put ECM based xenografts into clinical use, the induced inflammatory and immune responses have yet to be resolved. Cell membrane is embedded with membrane proteins for regulation of cell interactions including self-recognition and potent in reducing foreign body rejections. In this study, a novel and facile method for evasion from immune system was developed by coating autologous red blood cell membrane as a disguise on xenogeneic ECM based tissue engineering graft surface. Porcine source Living Hyaline Cartilage Graft (LhCG) and decellularized LhCG (dLhCG) established by our group for cartilage tissue engineering were chosen as model grafts. The cell membrane coating was quite stable on xenografts with no obvious decrease in amount for 4 weeks. The autologous cell membrane coated xenograft has been proved to be recognized as "self" by immune system on cell, protein and gene levels according to the 14-day lasting in vivo study on rats with less inflammatory cells infiltrated and low inflammation-related cytokines gene expression, showing alleviated acute immune and inflammatory responses.

Biomimetic mineralization of novel hydroxyethyl cellulose/soy protein isolate scaffolds promote bone regeneration in vitro and in vivo

Although various strategies have been utilized to accelerate bone regeneration in bone tissue engineering (BTE), the treatment and repair of large bone defects remains a clinical challenge worldwide. Inspired by the natural extracellular matrix of bone tissue, organic-inorganic composite scaffolds with three-dimensional (3D) porous structures, sufficient mechanical properties, excellent cytocompatibility, osteoconductivity, and osteogenic potential have received considerable attention within the field of bone engineering. In this work, a novel epichlorohydrin (ECH)-crosslinked hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) porous bi-component scaffold (EHSS) with hydroxyapatite (HAp) functionalization (EHSS/HAp) was constructed for bone defect repair via the combination of lyophilization and in situ biomimetic mineralization. Systematic characterization experiments were performed to assess the morphology, HAp-forming properties, mechanical properties and degradation rate of the scaffold. The results indicated that the prepared scaffolds exhibited an interconnected porous structure, a biomimetic HAp coating on their surfaces, improved mechanical properties in compression and a controllable degradation rate. In particular, semiquantitative analysis showed that the calcium/phosphorus (Ca/P) ratio of EHSS/HAp with 70% SPI content (1.65) was similar to that of natural bone tissue (1.67) according to energy dispersive X-ray spectroscopy analysis. In vitro cell culture experiments indicated that the EHSS/HAp with 70% SPI content showed improved cytocompatibility and was suitable for MC3T3-E1 cell attachment, proliferation and growth. Consistently, in vitro osteogenic differentiation studies showed that EHSS/HAp with 70% SPI content can significantly accelerate the expression of osteogenesis-related genes (Col-1, Runx2, OPN, and OCN) during osteogenic differentiation of MC3T3-E1 cells. Furthermore, when applied to the repair of critical-sized cranial defects in a rat model, EHSS/HAp with 70% SPI was capable of significantly promoting tissue regeneration and integration with native bone tissue. Microscopic computed tomography (micro-CT) results demonstrated that the bone defect site was nearly occupied with newly formed bone at 12 weeks after implantation of EHSS/HAp with 70% SPI content into the defect. Hematoxylin and eosin (H&E) staining and Masson's trichrome staining of histological sections further confirmed that EHSS/HAp with 70% SPI markedly promoted new bone formation and maturation. Collectively, our results demonstrate the potential of EHSS/HAp scaffolds with 70% SPI for successful bone defect repair and regeneration.

Soy protein isolate supplemented silk fibroin nanofibers for skin tissue regeneration: Fabrication and characterization

Biocompatible soy protein isolate/silk fibroin (SPI/SF) nanofibrous scaffolds were successfully fabricated through electrospinning a novel protein blend SPI/SF. Prepared nanofibers were treated with ethanol vapor to obtain an improved water-stable structure. Fabricated scaffolds were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-VIS spectrophotometry and image analysis. The mean diameters of SPI/SF electrospun fibers were observed ranging between 71 and 160 nm. The scaffolds were found significantly stable for a prolong duration at the room temperature as well as at 37 °C, when placed in phosphate buffered saline, nutrient medium, and lysozyme-containing solution. The potential of fabricated scaffolds for skin tissue regeneration was evaluated by in vitro culturing of standard cell lines i.e., fibroblast cells (L929-RFP (red fluorescent protein) and NIH-3T3) and melanocytes (B16F10). The outcomes revealed that all the fabricated nanofibrous scaffolds were non-toxic towards normal mammalian cells. In addition, healing of full-thickness wound in rats within 14 days after treatment with a nanofibrous scaffold demonstrated its suitability as a potential wound dressing material. Interestingly, we found that nanofibers induced a noticeable reduction in the proliferation rate of B16F10 melanoma cells.

Status of Plant Protein-Based Green Scaffolds for Regenerative Medicine Applications

In recent decades, regenerative medicine has merited substantial attention from scientific and research communities. One of the essential requirements for this new strategy in medicine is the production of biocompatible and biodegradable scaffolds with desirable geometric structures and mechanical properties. Despite such promise, it appears that regenerative medicine is the last field to embrace green, or environmentally-friendly, processes, as many traditional tissue engineering materials employ toxic solvents and polymers that are clearly not environmentally friendly. Scaffolds fabricated from plant proteins (for example, zein, soy protein, and wheat gluten), possess proper mechanical properties, remarkable biocompatibility and aqueous stability which make them appropriate green biomaterials for regenerative medicine applications. The use of plant-derived proteins in regenerative medicine has been especially inspired by green medicine, which is the use of environmentally friendly materials in medicine. In the current review paper, the literature is reviewed and summarized for the applicability of plant proteins as biopolymer materials for several green regenerative medicine and tissue engineering applications.

Immunomodulatory Functions of Mesenchymal Stem Cells in Tissue Engineering

The inflammatory response to chronic injury affects tissue regeneration and has become an important factor influencing the prognosis of patients. In previous stem cell treatments, it was revealed that stem cells not only have the ability for direct differentiation or regeneration in chronic tissue damage but also have a regulatory effect on the immune microenvironment. Stem cells can regulate the immune microenvironment during tissue repair and provide a good "soil" for tissue regeneration. In the current study, the regulation of immune cells by mesenchymal stem cells (MSCs) in the local tissue microenvironment and the tissue damage repair mechanisms are revealed. The application of the concepts of "seed" and "soil" has opened up new research avenues for regenerative medicine. Tissue engineering (TE) technology has been used in multiple tissues and organs using its biomimetic and cellular cell abilities, and scaffolds are now seen as an important part of building seed cell microenvironments. The effect of tissue engineering techniques on stem cell immune regulation is related to the shape and structure of the scaffold, the preinflammatory microenvironment constructed by the implanted scaffold, and the material selection of the scaffold. In the application of scaffold, stem cell technology has important applications in cartilage, bone, heart, and liver and other research fields. In this review, we separately explore the mechanism of MSCs in different tissue and organs through immunoregulation for tissue regeneration and MSC combined with 3D scaffolds to promote MSC immunoregulation to repair damaged tissues.

Characterization of Soybean Protein Adhesives Modified by Xanthan Gum

The aim of this study was to provide a basis for the preparation of medical adhesives from soybean protein sources. Soybean protein (SP) adhesives mixed with different concentrations of xanthan gum (XG) were prepared. Their adhesive features were evaluated by physicochemical parameters and an in vitro bone adhesion assay. The results showed that the maximal adhesion strength was achieved in 5% SP adhesive with 0.5% XG addition, which was 2.6-fold higher than the SP alone. The addition of XG significantly increased the hydrogen bond and viscosity, as well as increased the β-sheet content but decreased the α-helix content in the second structure of protein. X-ray diffraction data showed significant interactions between SP molecules and XG. Scanning electron microscopy observations showed that the surface of SP adhesive modified by XG was more viscous and compact, which were favorable for the adhesion between the adhesive and bone. In summary, XG modification caused an increase in the hydrogen bonding and zero-shear viscosity of SP adhesives, leading to a significant increase in the bond strength of SP adhesives onto porcine bones.

Bio-Based Polymers for 3D Printing of Bioscaffolds

Three-dimensional (3D) printing technologies enable not only faster bioconstructs development but also on-demand and customized manufacturing, offering patients a personalized biomedical solution. This emerging technique has a great potential for fabricating bioscaffolds with complex architectures and geometries and specifically tailored for use in regenerative medicine. The next major innovation in this area will be the development of biocompatible and histiogenic 3D printing materials with bio-based printable polymers. This review will briefly discuss 3D printing techniques and their current limitations, with a focus on novel bio-based polymers as 3D printing feedstock for clinical medicine and tissue regeneration.

Immune response of bovine sourced cross-linked collagen sponge for hemostasis

A comprehensive immunogenicity scheme is proposed to examine immune response of bovine sourced hemostasis collagen sponge to establish foundation for further researches and decrease the incidence of adverse reaction in clinical trials. Compared with negative control group without any implant, spleen and lymph nodes morphology show no apparent swelling in mice with different doses of collagen sponge implants. Immune cells population, especially lymph nodes cells population, is practically coincident with organs. However, splenic cells display slight proliferation in early phase following collagen sponge implantation. Splenic cells apoptosis also demonstrates no significant difference among all groups. T lymphocytes subsets, CD4/CD8 cells ratio, in spleen and lymph nodes are practically normal. Splenic cells Ki67 + proportions do not exhibit significant difference between collagen sponge groups and negative control group. Humoral response is determined by detection of IgG and IgM concentration in serum, not exhibiting remarkable increase with collagen sponge implantation, compared to the drastic increase in positive control group with bovine tendon implantation. Local analysis around implants by hematoxylin-eosin staining discovers slight cell infiltration around collagen sponge. Tumour necrosis factor-α immunostaining indicates slight inflammation in early phase following collagen sponge implantation, but interferon-γ immunostaining is negligible even in positive control group. Collagen sponge, especially in high dose, may have evoked benign immune response in BALB/c mice, but this response is transient. The present evaluation scheme for immune response is integrated and comprehensive, suitable for various biomaterials.

Recent advances in bioprinting techniques: approaches, applications and future prospects

Bioprinting technology shows potential in tissue engineering for the fabrication of scaffolds, cells, tissues and organs reproducibly and with high accuracy. Bioprinting technologies are mainly divided into three categories, inkjet-based bioprinting, pressure-assisted bioprinting and laser-assisted bioprinting, based on their underlying printing principles. These various printing technologies have their advantages and limitations. Bioprinting utilizes biomaterials, cells or cell factors as a "bioink" to fabricate prospective tissue structures. Biomaterial parameters such as biocompatibility, cell viability and the cellular microenvironment strongly influence the printed product. Various printing technologies have been investigated, and great progress has been made in printing various types of tissue, including vasculature, heart, bone, cartilage, skin and liver. This review introduces basic principles and key aspects of some frequently used printing technologies. We focus on recent advances in three-dimensional printing applications, current challenges and future directions.

Keratin hydrogel carrier system for simultaneous delivery of exogenous growth factors and muscle progenitor cells

Ideal material characteristics for tissue engineering or regenerative medicine approaches to volumetric muscle loss (VML) include the ability to deliver cells, growth factors, and molecules that support tissue formation from a system with a tunable degradation profile. Two different types of human hair-derived keratins were tested as options to fulfill these VML design requirements: (1) oxidatively extracted keratin (keratose) characterized by a lack of covalent crosslinking between cysteine residues, and (2) reductively extracted keratin (kerateine) characterized by disulfide crosslinks. Human skeletal muscle myoblasts cultured on coatings of both types of keratin had increased numbers of multinucleated cells compared to collagen or Matrigel(TM) and adhesion levels greater than collagen. Rheology showed elastic moduli from 10(2) to 10(5) Pa and viscous moduli from 10(1) to 10(4) Pa depending on gel concentration and keratin type. Kerateine and keratose showed differing rates of degradation due to the presence or absence of disulfide crosslinks, which likely contributed to observed differences in release profiles of several growth factors. In vivo testing in a subcutaneous mouse model showed that keratose hydrogels can be used to deliver mouse muscle progenitor cells and growth factors. Histological assessment showed minimal inflammatory responses and an increase in markers of muscle formation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 864-879, 2016.

Three-dimensional scaffold of gelatin–poly(methyl vinyl ether-alt-maleic anhydride) for regenerative medicine: Proliferation and differentiation of mesenchymal stem cells

Cell-based tissue engineering offers great promise to regenerative therapy, but so far it has been restricted due to insufficient number of cells obtained from donors and the lack of efficient ways of delivering them to target sites. This study shows, for the first time, the ability of a composite scaffold of gelatin and poly(methyl vinyl ether- alt-maleic anhydride) (GP-2) as a niche for expansion and multilineage differentiation ability of human umbilical cord–derived mesenchymal stem cells. First, the in vivo biocompatibility of scaffolds was checked by subcutaneous implantation of scaffolds in male Wistar rats for up to 45 days. Hematological parameters and histology of skin near implanted region rule out the probability of any adverse effects due to the scaffolds. The isolated human umbilical cord–derived mesenchymal stem cells were seeded on to pre-optimized scaffolds and induced to differentiate into osteogenic and adipogenic lineages by culturing in respective induction media. The human umbilical cord–derived mesenchymal stem cells were found to be viable and proliferated well on scaffolds when assessed with live/dead and PicoGreen assay. The biochemical assays such as alkaline phosphatase activity and triglycerides estimation confirmed the differentiation of cells toward particular lineages when cultured on scaffolds with appropriate inductive media. The study exhibited the proficiency of scaffold GP-2 for mesenchymal stem cells’ adherence, proliferation, and differentiation and also showed its engraftment efficiency. Taken together, our study establishes the in vivo biocompatibility of composite scaffold and, importantly, indicates its potential for stem cell–based therapy.

Biomedical applications of soy protein: A brief overview

Soy protein (SP) based materials are gaining increasing interest for biomedical applications because of their tailorable biodegradability, abundance, being relatively inexpensive, exhibiting low immunogenicity, and for being structurally similar to components of the extracellular matrix (ECM) of tissues. Analysis of the available literature indicates that soy protein can be fabricated into different shapes, being relatively easy to be processed by solvent or melt based techniques. Furthermore soy protein can be blended with other synthetic and natural polymers and with inorganic materials to improve the mechanical properties and the bioactive behavior for several demands. This review discusses succinctly the biomedical applications of SP based materials focusing on processing methods, properties and applications highlighting future avenues for research.

Culturing fibroblasts in 3D human hair keratin hydrogels

Human hair keratins are readily available, easy to extract, and eco-friendly materials with natural bioactivities. Keratin-based materials have been studied for applications such as cell culture substrates, internal hemostats for liver injury, and conduits for peripheral nerve repair. However, there are limited reports of using keratin-based 3D scaffolds for cell culture in vitro. Here, we describe the development of a 3D hair keratin hydrogel, which allows for living cell encapsulation under near physiological conditions. The convenience of making the hydrogels from keratin solutions in a simple and controllable manner is demonstrated, giving rise to constructs with tunable physical properties. This keratin hydrogel is comparable to collagen hydrogels in supporting the viability and proliferation of L929 murine fibroblasts. Notably, the keratin hydrogels contract less significantly as compared to the collagen hydrogels, over a 16-day culture period. In addition, preliminary in vivo studies in immunocompetent animals show mild acute host tissue response. These results collectively demonstrate the potential of cell-loaded keratin hydrogels as 3D cell culture systems, which may be developed for clinically relevant applications.

Recent advances in 3D printing of biomaterials

3D Printing promises to produce complex biomedical devices according to computer design using patient-specific anatomical data. Since its initial use as pre-surgical visualization models and tooling molds, 3D Printing has slowly evolved to create one-of-a-kind devices, implants, scaffolds for tissue engineering, diagnostic platforms, and drug delivery systems. Fueled by the recent explosion in public interest and access to affordable printers, there is renewed interest to combine stem cells with custom 3D scaffolds for personalized regenerative medicine. Before 3D Printing can be used routinely for the regeneration of complex tissues (e.g. bone, cartilage, muscles, vessels, nerves in the craniomaxillofacial complex), and complex organs with intricate 3D microarchitecture (e.g. liver, lymphoid organs), several technological limitations must be addressed. In this review, the major materials and technology advances within the last five years for each of the common 3D Printing technologies (Three Dimensional Printing, Fused Deposition Modeling, Selective Laser Sintering, Stereolithography, and 3D Plotting/Direct-Write/Bioprinting) are described. Examples are highlighted to illustrate progress of each technology in tissue engineering, and key limitations are identified to motivate future research and advance this fascinating field of advanced manufacturing.

Pre-clinical evaluation of soybean-based wound dressings and dermal substitute formulations in pig healing and non-healing in vivo models

In the last decade, a new class of natural biomaterials derived from de-fatted soybean flour processed by either thermoset or extraction procedures has been developed. These biomaterials uniquely combine adaptability to various clinical applications to proven tissue regeneration properties. In the present work, the biomaterials were formulated either as hydrogel or as paste formulation and their potential as wound dressing material or as dermal substitute was assessed by two in vivo models in pig skin: The healing full-thickness punch biopsy model and the non-healing full-thickness polytetrafluoroethylene (PTFE) chamber model. The results clearly show that collagen deposition is induced by the presence of these biomaterials. A unique pattern of early inflammatory response, eliciting neutrophils and controlling macrophage infiltration, is followed by tissue cell colonization of the wound bed with a significant deposition of collagen fibers. The study also highlighted the importance in the use of optimal formulations and appropriate handling upon implantation. In large size, non-healing wounds, wound dermis was best obtained with the paste formulation as hydrogels appeared to be too loose to ensure lasting scaffolding properties. On the contrary, packing of the granules during the application of paste reduced biomaterial degradation rate and prevent the penetration of newly vascularized tissue, thus impeding grafting of split-thickness autologous skin grafts on the dermal substitute base.