Bioprinted Skin Research Articles

Methodologies of Autologous Skin Cell Spray Graft.

Healthcare workers continue to struggle with skin wound management. Despite the fact that there have been many methods created throughout the decades for skin regeneration, contemporary developments in regenerative medicine provide highly reliable methods for creating synthetic skin replacements, such as electrospinning, 3D bioprinting, or spraying, among all others. Specifically, skin sprays have been a cutting-edge method that is currently undergoing clinical testing and has lots of promise for providing cells and hydrogels to cure both acute and chronic wounds. Deposition of cells and scaffolding materials in successive layers over the burnt regions characterises 3D bioprinting for burn injury repair. Depending on the desired outcome, bioprinting of skin may be performed in vivo or in vitro. However, the location of the printing and the time required for the tissue to mature separates these two methods. Bioprinted skin for use in burn repair faces technical and regulatory hurdles before it may be used in clinical settings. Skin sprays provide various benefits to traditional wound care methods, inclusive of ease of administration, the ability to treat broad wound regions, and a consistent dispersion of the sprayed substance. The most recent developments in this technology are reviewed in this article, along with a thorough explanation of investigational and presently marketed acellular and cellular skin spray solutions that are utilized to treat a range of illnesses and administer various experimental materials. Additionally, we describe regulatory processes for their capitalization and cover key clinical studies for various skin illnesses and associated treatment circumstances because skin spray products are susceptible to several classifications. Finally, we provide an argument and offer potential future developments in the biotechnology of skin sprays for improved clinical dermatological applications.

Properties of Collagen/Sodium Alginate Hydrogels for Bioprinting of Skin Models

3D printing technology has great potential for the reconstruction of human skin. However, the reconstructed skin has some differences from natural skin, largely because the hydrogel used does not have the appropriate biological and physical properties to allow healing and regeneration. This study examines the swelling, degradability, microstructure and biological properties of Collagen/Sodium Alginate (Col/SA) hydrogels of differing compositions for the purposes of skin printing. Increasing the content of sodium alginate causes the hydrogel to exhibit stronger mechanical and swelling properties, a faster degradation ratio, smaller pore size, and less favorable biological properties. An optimal 1% collagen hydrogel was used to print bi-layer skin in which fibroblasts and keratinocytes showed improved spreading and proliferation as compared to other developed formulations. The Col/SA hydrogels presented suitable tunability and properties to be used as a bioink for bioprinting of skin aiming at finding applications as 3D models for wound healing research.

A bioprinted vascularized skin substitute with fibroblasts, keratinocytes, and endothelial progenitor cells for skin wound healing

Skin substitutes are highly demanded by patients with extensive burns and full-thickness skin wounds. Bioprinting offers a promising technology to fabricate customized cell-laden skin substitutes. In this study, a hydrogel of biodegradable polyurethane (PU)-gelatin (4:1) laden with human fibroblasts, endothelial progenitor cells (EPCs), and keratinocytes was used as the bioink for building a bi-layer dermo-epidermal skin substitute. The seven-layer cell-laden constructs with stack thickness of 1.4 mm were precisely deposited through a 210 μm nozzle with an air pressure of 0.055–0.175 MPa and nozzle temperature of 19 °C. When grown in vitro, three types of cells in the bioprinted constructs showed good cell viability (>99%) in 24 h and reached a high proliferation rate (>220%) in 14 days. Significantly, EPCs were successfully differentiated into endothelial-like cells in the constructs and expressed the vasculogenesis-related proteins (CD31+ and eNOS+). When implanted in vivo, the bi-layer constructs attained ∼90% wound healing ratio and ∼76% re-epithelialization after 28 days in the nude mice model. Histological analyses revealed that skin wounds treated with the bi-layer constructs achieved high degrees of tissue integration and collagen production after 28 days. Vasculogenesis and angiogenesis of the wound treated with bi-layer constructs was significantly greater (∼300%) than those of the untreated wounds. The in vitro and in vivo findings indicate that the bioprinted skin substitutes with fibroblasts, EPCs, and keratinocytes embedded in PU-gelatin hydrogel may offer a promising strategy for clinical wound treatment and development of bioprinted skin.

Innovative Treatment Strategies to Accelerate Wound Healing: Trajectory and Recent Advancements.

Wound healing is highly specialized dynamic multiple phase process for the repair of damaged/injured tissues through an intricate mechanism. Any failure in the normal wound healing process results in abnormal scar formation, and chronic state which is more susceptible to infections. Chronic wounds affect patients’ quality of life along with increased morbidity and mortality and are huge financial burden to healthcare systems worldwide, and thus requires specialized biomedical intensive treatment for its management. The clinical assessment and management of chronic wounds remains challenging despite the development of various therapeutic regimens owing to its painstakingly long-term treatment requirement and complex wound healing mechanism. Various conventional approaches such as cell therapy, gene therapy, growth factor delivery, wound dressings, and skin grafts etc., are being utilized for promoting wound healing in different types of wounds. However, all these abovementioned therapies are not satisfactory for all wound types, therefore, there is an urgent demand for the development of competitive therapies. Therefore, there is a pertinent requirement to develop newer and innovative treatment modalities for multipart therapeutic regimens for chronic wounds. Recent developments in advanced wound care technology includes nanotherapeutics, stem cells therapy, bioengineered skin grafts, and 3D bioprinting-based strategies for improving therapeutic outcomes with a focus on skin regeneration with minimal side effects. The main objective of this review is to provide an updated overview of progress in therapeutic options in chronic wounds healing and management over the years using next generation innovative approaches. Herein, we have discussed the skin function and anatomy, wounds and wound healing processes, followed by conventional treatment modalities for wound healing and skin regeneration. Furthermore, various emerging and innovative strategies for promoting quality wound healing such as nanotherapeutics, stem cells therapy, 3D bioprinted skin, extracellular matrix-based approaches, platelet-rich plasma-based approaches, and cold plasma treatment therapy have been discussed with their benefits and shortcomings. Finally, challenges of these innovative strategies are reviewed with a note on future prospects.

832 3D Bioprinted vascularized human skin models can be used to screen modulators of angiogenesis for medical and dermo-cosmetic applications

Lack of skin vascularization or in contrast its hypervascularization are aggravating factors of some medical pathologies (ulcers and cancers) and dermo-cosmetics troubles (rosacea and dark circles). Thus, developing a suitable in vitro model to screen pharmaceutical and cosmetics ingredients able to stimulate or mitigate the angiogenesis process without changing the normal skin physiology are not easy and hampered by the existence of unreliable in vitro models. Traditional models of skin angiogenesis concentrate on analyzing the co-culture growth of endothelial cells with or without added fibroblasts or keratinocytes. However, these models do not work for topical applications and top-down layering analysis required for complex studies and do not translate well to clinical analysis. Here we describe the creation of a 3D bioprinted vascularized skin model, designed for screening those type of molecules. Human Dermal Microvascular Endothelial Cells, dermal fibroblasts and epidermal keratinocytes were harvested and expanded from juvenile foreskins. Cells were selected for optimal growth and mixed with a bioink into which adhesion proteins were added and cartridged into a CELLINK pneumatic 3D bioprinting system allowing the generation of 3D vascularized printed full thickness skins. Resulting skin models had a vascularization bed created in the lower quadrant of the dermal structure, which was confocal microscopy imaged with anti-CD31 fluorescent labelling. Reduction of epidermal growth factor and pituitary supplement resulted in the sequential reduction and cell death of the vascular bed over 14 days, whilst continual supplementation maintains the model and cellular interconnections. With 3D Bioprinting we can produce hundreds of models in one afternoon giving the potential to screen many combinations of molecules before moving to more expensive clinical experimentations.

782 Characterization of mechano-biological pathways involved in bioprinted skin remodeling

Reorganization of fibrin is the first stage in the matrix maturation process of bioprinted skin and takes place over a few hours to a few days. Fibrin is a popular component of many bioinks and a provisional component of the extracellular matrix present during wound healing. Cells embedded in fibrin gels attach and exert traction forces to realign and/or degrade the fibrin fibers, and sense and respond to the surrounding substrate in a mechanical feedback loop. Such cellular actions may remodel the printed construct in such a way, rendering it no longer feasible for implantation.

780 Multicellular bioprinted skin directs the formation of human-like epidermal architecture and capillary formation in full-thickness wounds

Current skin substitutes fail to meet the need for skin replacement in full-thickness wounds. Bioprinting is a promising alternative method to generate skin substitutes, as it can replicate the structural organization of the skin into biomimetic layers. In prior studies, we demonstrated that wounds treated with bioprinted skin had accelerated wound healing driven by epithelialization with reduced contraction and immunofluorescent staining demonstrated a mixed composition of human and mouse cells in the healing wounds.

3D Bio-printing For Skin Tissue Regeneration: Hopes and Hurdles.

For many years, discovering the appropriate methods for the treatment of skin irritation has been challenging for specialists and researchers. Bio-printing can be extensively applied to address the demand for proper skin substitutes to improve skin damage. Nowadays, to make more effective biomimicry of natural skin, many research teams have developed cell-seeded bio-inks for bioprinting of skin substitutes. These loaded cells can be single or co-cultured in these structures. The present review gives a comprehensive overview of the methods, substantial parameters of skin bioprinting, examples of in vitro and in vivo studies, and current advances and challenges in skin tissue engineering.

Future prospects in 3-dimensional (3D) technology and Mohs micrographic surgery

The advancement of three-dimensional (3D) bioprinting has allowed for changes within the field of dermatology. Skin bioprinting is a transformative technology used to fabricate biomimetic scaffold architectures which mimic human skin. This paper briefly discusses three major types of biological printing: inkjet-based bioprinting, laser-assisted bioprinting and pressure-assisted bioprinting in regard to skin bioprinting for Mohs application. This manuscript reviews the basic principles of 3D printing (inkjet-based bioprinting, laser-assisted bioprinting and pressure-assisted bioprinting), current 3D skin bioprinting applications and methods, and perspectives on using 3D printing for Mohs surgery.

3D bioprinting of an implantable xeno-free vascularized human skin graft.

Bioengineered tissues or organs produced using matrix proteins or components derived from xenogeneic sources pose risks of allergic responses, immune rejection, or even autoimmunity. Here, we report successful xeno-free isolation, expansion, and cryopreservation of human endothelial cells (EC), fibroblasts (FBs), pericytes (PCs), and keratinocytes (KCs). We further demonstrate the bioprinting of a human skin substitute with a dermal layer containing xeno-free cultured human EC, FBs, and PCs in a xeno-free bioink containing human collagen type I and fibronectin layered in a biocompatible polyglycolic acid mesh and subsequently seeded with xeno-free human KCs to form an epidermal layer. Following implantation of such bilayered skin grafts on the dorsum of immunodeficient mice, KCs form a mature stratified epidermis with rete ridge-like structures. The ECs and PCs form human EC-lined perfused microvessels within 2 weeks after implantation, preventing graft necrosis, and eliciting further perfusion of the graft by angiogenic host microvessels. As proof-of-concept, we generated 12 individual grafts using a single donor of all four cell types. In summary, we describe the fabrication of a bioprinted vascularized bilayered skin substitute under completely xeno-free culture conditions demonstrating feasibility of a xeno-free approach to complex tissue engineering.

Innovations in Stem Cell Therapy for Diabetic Wound Healing.

Significance: The global burden of diabetic wounds, particularly diabetic foot ulcers, continues to have large economic and social impact throughout the world. Current strategies are not sufficient to overcome this burden of disease. Finding newer, more advanced regenerative cell and tissue-based strategies to reduce morbidity remains paramount. Recent Advances: Recent advances in stem cell therapies are discussed. We also highlight the practical issues of translating these advancing technologies into the clinical setting. Critical Issues: We discuss the use of somatic and induced pluripotent stem cells and the stromal vascular fraction, as well as innovations, including the use of 3D bioprinting of skin. We also explore related issues of using regenerative techniques in clinical practice, including the current regulatory landscape and translatability of in vivo research. Future Directions: Advances in stem cell manipulation showcase the best therapeutic resources available to enhance mechanisms of wound healing such as angiogenesis, cell proliferation, and collagen synthesis; potential methods include changing the scaffold microenvironment, including relative oxygen tension, and the use of gene modification and nanotechnology. Secretome engineering, particularly the use of extracellular vesicles, may be another potential cell-derived therapeutic that may enable use of cell-free translational therapy.

Simple and robust 3D bioprinting of full-thickness human skin tissue

ABSTRACT Artificial skins have been used as skin substitutes for wound healing in the clinic, and as in vitro models for safety assessment in cosmetic and pharmaceutical industries. The three-dimensional (3D) bioprinting technique provides a promising strategy in the fabrication of artificial skins. Despite the technological advances, many challenges remain to be conquered, such as the complicated preparation conditions for bio-printed skin and the unavailability of stability and robustness of skin bioprinting. Here, we formulated a novel bio-ink composed of gelatin, sodium alginate and fibrinogen. By optimizing the ratio of components in the bio-ink, the design of the 3D model and the printing conditions, a fibroblasts-containing dermal layer construct was firstly fabricated, on the top of which laminin and keratinocytes were sequentially placed. Through air-liquid interface (ALI) culture by virtue of sterile wire mesh, a full-thickness skin tissue was thus prepared. HE and immunofluorescence staining showed that the bio-printed skin was not only morphologically representative of the human skin, but also expressed the specific markers related to epidermal differentiation and stratum corneum formation. The presented easy and robust preparation of full-thickness skin constructs provides a powerful tool for the establishment of artificial skins, holding critical academic significance and application value.

Tailoring bioinks of extrusion-based bioprinting for cutaneous wound healing.

Extrusion-based bioprinting (EBB) holds potential for regenerative medicine. However, the widely-used bioinks of EBB exhibit some limitations for skin regeneration, such as unsatisfactory bio-physical (i.e., mechanical, structural, biodegradable) properties and compromised cellular compatibilities, and the EBB-based bioinks with therapeutic effects targeting cutaneous wounds still remain largely undiscussed. In this review, the printability considerations for skin bioprinting were discussed. Then, current strategies for improving the physical properties of bioinks and for reinforcing bioinks in EBB approaches were introduced, respectively. Notably, we highlighted the applications and effects of current EBB-based bioinks on wound healing, wound scar formation, vascularization and the regeneration of skin appendages (i.e., sweat glands and hair follicles) and discussed the challenges and future perspectives. This review aims to provide an overall view of the applications, challenges and promising solutions about the EBB-based bioinks for cutaneous wound healing and skin regeneration.

Developing a bioprintable epidermis

Burn patients suffer extensive damage to their skin that initially require rapid intervention for their survival, with the focus then shifting to improved functional outcomes upon healing. Current treatments involve surgical excision of the burned skin and reconstruction of the wound with the aid of skin autografts and skin substitutes. However, these treatments have limitations, the first being limited donor site skin autografts that in turn lead to donor site morbidity; the latter being immune rejections and failure of skin substitutes to thrive. Recent advances in bioprinting technology have led researchers to explore its use to fabricate skin grafts, which depends on several factors, including appropriate bioinks, cell types and printing methods. Although there are many bioprinters commercially available, they are typically intended for printing constructs for research use. While there are some research efforts into developing skin bioprinting intended for clinical use, there are lingering usability issues that will likely limit their adoption. In this paper, we discuss our work in designing an in situ skin bioprinting workflow, comprising an ergonomic handheld bioprinter, combined with bioink formulated to form the mature epidermis without the need for further manipulation or intervention. This method may allow the deposition of a contiguous layer of the keratinocyte bioink directly onto the wound, which could revolutionise how burn wounds are reconstructed and possibly result in a paradigm shift in healed burn wounds outcome.

3D Bioprinting of Heterogeneous Tissue-Engineered Skin Containing Human Dermal Fibroblasts and Keratinocytes

3D Bioprinting of Heterogeneous Tissue-Engineered Skin Containing Human Dermal Fibroblasts and Keratinocytes

A Bioprinted Vascularized Skin Substitute with Fibroblasts, Keratinocytes, and Endothelial Progenitor Cells for Skin Wound Healing

A Bioprinted Vascularized Skin Substitute with Fibroblasts, Keratinocytes, and Endothelial Progenitor Cells for Skin Wound Healing

3D Bioprinting in Skin Related Research: Recent Achievements and Application Perspectives.

In recent years, significant progress has been observed in the field of skin bioprinting, which has a huge potential to revolutionize the way of treatment in injury and surgery. Furthermore, it may be considered as an appropriate platform to perform the assessment and screening of cosmetic and pharmaceutical formulations. Therefore, the objective of this paper was to review the latest advances in 3D bioprinting dedicated to skin applications. In order to explain the boundaries of this technology, the architecture and functions of the native skin were briefly described. The principles of bioprinting methods were outlined along with a detailed description of key elements that are required to fabricate the skin equivalents. Next, the overview of recent progress in 3D bioprinting studies was presented. The article also highlighted the potential applications of bioengineered skin substituents in various fields including regenerative medicine, modeling of diseases, and cosmetics/drugs testing. The advantages, limitations, and future directions of this technology were also discussed.

Potential of three-dimensional bioprinting in oral soft tissue engineering applications

Oral soft tissue engineering involves the reconstruction or restoration of oral and maxillofacial functions and esthetics. As an emerging technology from the early 21st century, three-dimensional (3D) bioprinting promises great application potentials in the preparation of scaffolds and engineered tissues/organs. Although oral soft tissues include dental pulp, periodontal ligament, gum, oral mucosa, and salivary glands as well as related maxillofacial skin, vascular, muscular, and neuronal tissues, the current application of 3D bioprinting in oral soft tissue-restoration is mainly limited to dental pulp-regeneration. Different bioinks are used to load dental pulp cells into the dentin matrix for restoring the dental pulp tissue; 3D bioprinting has only been reported in a few in vitro studies on periodontal ligament-reconstruction and salivary gland culture; and 3D bioprinting used towards regenerating gingival tissue/oral mucosa has not been demonstrated. The limited application of 3D bioprinting in oral soft tissue engineering is perhaps related to the complex, fine, and orderly structure of the periodontal ligament, the moist environment of the oral cavity, the small operating space, and the continuous chewing pressure. The studies on bioprinting of skin, vascular, muscular, and neuronal tissues are broad, but they are typically not oral-specific. This article introduces the current application status and prospects of 3D bioprinting in the regeneration of oral soft tissues, using cytocompatible hydrogels as bioinks.

3D Bioprinted Skin Substitutes for Accelerated Wound Healing and Reduced Scar

3D Bioprinted Skin Substitutes for Accelerated Wound Healing and Reduced Scar

Perspective: 3D bioprinted skin - engineering the skin for medical applications

Perspective: 3D bioprinted skin - engineering the skin for medical applications