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Collagen is a cornerstone protein for tissue engineering and 3D bioprinting due to its outstanding biocompatibility, low immunogenicity, and natural abundance in human tissues. Nonetheless, it still poses some important challenges, such as complicated and limited extraction processes, usually accompanied by batchto-batch reproducibility and influence of factors, such as temperature, pH, and ionic strength. In this work, we evaluated the suitability and performance of new, fibrillar type I collagen as standardized and reproducible collagen source for 3D printing and bioprinting. The acidic, native fibrous collagen formulation (5% w/w) performed remarkably during 3D printing, which was possible to print constructs of up to 27 layers without collapsing. On the other hand, the fibrous collagen mass has been modified to provide a fast, reliable, and easily neutralizable process. The neutralization with TRIS-HCl enabled the inclusion of cells without hindering printability. The cell-laden constructs were printed under mild conditions (50–80 kPa, pneumatic 3D printing), providing remarkable cellular viability (>90%) as well as a stable platform for cell growth and proliferation in vitro. Therefore, the native, type I collagen masses characterized in this work offer a reproducible and reliable source of collagen for 3D printing and bioprinting purposes.

Drug adherence is a significant medical issue, often responsible for sub-optimal outcomes during the treatment of chronic diseases such as rheumatoid or psoriatic arthritis. Monoclonal antibodies (which are exclusively given parenterally) have been proven to be an effective treatment in these cases. The use of auto-injectors is an effective strategy to improve drug adherence in parenteral treatments since these pen-like devices offer less discomfort and increased user-friendliness over conventional syringe-based delivery. This study aims to investigate the feasibility of including a monoclonal antibody as a solid formulation inside an auto-injector pen. Specifically, the objective was to evaluate the drug stability after a concentration (to reduce the amount of solvent and space needed) and freeze-drying procedure. A preliminary screening of excipients to improve stability was also performed. The nano-DSC results showed that mannitol improved the stability of the concentrated, freeze-dried antibody in comparison to its counterpart without it. However, a small instability of the CH2 domain was still found for mannitol samples, which will warrant further investigation. The present results serve as a stepping stone towards advancing future drug delivery systems that will ultimately improve the patient experience and associated drug adherence.

Vascular stents (VS) have revolutionized the treatment of cardiovascular diseases, as evidenced by the fact that the implantation of VS in coronary artery disease (CAD) patients has become a routine, easily approachable surgical intervention for the treatment of stenosed blood vessels. Despite the evolution of VS throughout the years, more efficient approaches are still required to address the medical and scientific challenges, especially when it comes to peripheral artery disease (PAD). In this regard, three-dimensional (3D) printing is envisaged as a promising alternative to upgrade VS by optimizing the shape, dimensions and stent backbone (crucial for optimal mechanical properties), making them customizable for each patient and each stenosed lesion. Moreover, the combination of 3D printing with other methods could also upgrade the final device. This review focuses on the most recent studies using 3D printing techniques to produce VS, both by itself and in combination with other techniques. The final aim is to provide an overview of the possibilities and limitations of 3D printing in the manufacturing of VS. Furthermore, the current situation of CAD and PAD pathologies is also addressed, thus highlighting the main weaknesses of the already existing VS and identifying research gaps, possible market niches and future directions.

Osteochondral injuries can lead to osteoarthritis (OA). OA is characterized by the progressive degradation of the cartilage tissue together with bone tissue turnover. Consequently, joint pain, inflammation, and stiffness are common, with joint immobility and dysfunction being the most severe symptoms. The increase in the age of the population, along with the increase in risk factors such as obesity, has led OA to the forefront of disabling diseases. In addition, it not only has an increasing prevalence, but is also an economic burden for health systems. Current treatments are focused on relieving pain and inflammation, but they become ineffective as the disease progresses. Therefore, new therapeutic approaches, such as tissue engineering and 3D bioprinting, have emerged. In this review, the advantages of using 3D bioprinting techniques for osteochondral regeneration are described. Furthermore, the biomaterials, cell types, and active molecules that are commonly used for these purposes are indicated. Finally, the most recent promising results for the regeneration of cartilage, bone, and/or the osteochondral unit through 3D bioprinting technologies are considered, as this could be a feasible therapeutic approach to the treatment of OA.

Bone tissue is usually damaged after big traumas, tumors, and increasing aging-related diseases such as osteoporosis and osteoarthritis. Current treatments are based on implanting grafts, which are shown to have several inconveniences. In this regard, tissue engineering through the 3D bioprinting technique has arisen to manufacture structures that would be a feasible therapeutic option for bone regenerative medicine. In this study, nanocellulose–alginate (NC–Alg)-based bioink is improved by adding two different inorganic components such as hydroxyapatite (HAP) and graphene oxide (GO). First, ink rheological properties and biocompatibility are evaluated as well as the influence of the sterilization process on them. Then, scaffolds are characterized. Finally, biological studies of embedded murine D1 mesenchymal stem cells engineered to secrete erythropoietin are performed. Results show that the addition of both HAP and GO prevents NC–Alg ink from viscosity lost in the sterilization process. However, GO is reduced due to short cycle autoclave sterilization, making it incompatible with this ink. In addition, HAP and GO have different influences on scaffold architecture and surface as well as in swelling capacity. Scaffolds mechanics, as well as cell viability and functionality, are promoted by both elements addition. Additionally, GO demonstrates an enhanced bone differentiation capacity.

In the last few years, attempts to improve the regeneration of damaged tendons have been rising due to the growing demand. However, current treatments to restore the original performance of the tissue focus on the usage of grafts; although, actual grafts are deficient because they often cannot provide enough support for tissue regeneration, leading to additional complications. The beneficial effect of combining 3D bioprinting and dECM as a novel bioink biomaterial has recently been described. Tendon dECMs have been obtained by using either chemical, biological, or/and physical treatments. Although decellularization protocols are not yet standardized, recently, different protocols have been published. New therapeutic approaches embrace the use of dECM in bioinks for 3D bioprinting, as it has shown promising results in mimicking the composition and the structure of the tissue. However, major obstacles include the poor structural integrity and slow gelation properties of dECM bioinks. Moreover, printing parameters such as speed and temperature have to be optimized for each dECM bioink. Here, we show that dECM bioink for 3D bioprinting provides a promising approach for tendon regeneration for future clinical applications.

The adaptation and progress of 3D printing technology toward 3D bioprinting (specifically adapted to biomedical purposes) has opened the door to a world of new opportunities and possibilities in tissue engineering and regenerative medicine. In this regard, 3D bioprinting allows for the production of tailor-made constructs and organs as well as the production of custom implants and medical devices. As it is a growing field of study, currently, the attention is heeded on the optimization and improvement of the mechanical and biological properties of the so-called bioinks/biomaterial inks. One of the strategies proposed is the use of inorganic ingredients (clays, hydroxyapatite, graphene, carbon nanotubes and other silicate nanoparticles). Clays have proven to be useful as rheological and mechanical reinforcement in a wide range of fields, from the building industry to pharmacy. Moreover, they are naturally occurring materials with recognized biocompatibility and bioactivity, revealing them as optimal candidates for this cutting-edge technology. This review deals with the use of clays (both natural and synthetic) for tissue engineering and regenerative medicine through 3D printing and bioprinting. Despite the limited number of studies, it is possible to conclude that clays play a fundamental role in the formulation and optimization of bioinks and biomaterial inks since they are able to improve their rheology and mechanical properties, thus improving printability and construct resistance. Additionally, they have also proven to be exceptionally functional ingredients (enhancing cellular proliferation, adhesion, differentiation and alignment), controlling biodegradation and carrying/releasing actives with tissue regeneration therapeutic activities.

Three-dimensional (3D) printing is a game changer technology that holds great promise for a wide variety of biomedical applications, including ophthalmology. Through this emerging technique, specific eye tissues can be custom-fabricated in a flexible and automated way, incorporating different cell types and biomaterials in precise anatomical 3D geometries. However, and despite the great progress and possibilities generated in recent years, there are still challenges to overcome that jeopardize its clinical application in regular practice. The main goal of this review is to provide an in-depth understanding of the current status and implementation of 3D bioprinting technology in the ophthalmology field in order to manufacture relevant tissues such as cornea, retina and conjunctiva. Special attention is paid to the description of the most commonly employed bioprinting methods, and the most relevant eye tissue engineering studies performed by 3D bioprinting technology at preclinical level. In addition, other relevant issues related to use of 3D bioprinting for ocular drug delivery, as well as both ethical and regulatory aspects, are analyzed. Through this review, we aim to raise awareness among the research community and report recent advances and future directions in order to apply this advanced therapy in the eye tissue regeneration field.

Tendon injuries represent a clinical burden on health systems globally. 3D bioprinting could help for the development of scaffolds whose characteristics resemble those of the native tendon. In this study, an ink based on natural materials was developed for tendon tissue regeneration. That ink was characterized and used to print scaffolds by 3D printing. Swelling and degradation rate assays were performed to predict the possible behaviour of the scaffolds in vivo. Finally, tenocytes were incorporated into the inks and 3D bioprinted. The viability and metabolic activity of tenocytes in the scaffold were analyzed.

The incidence of bone-related diseases has been increasing due to aging of the population. Up to now, therapeutic approaches have been focused on graft and titanium implants, which have been associated with infection, pain and implant rejection. Tissue engineering has become a promising treatment due to the use of scaffolds, which are designed to imitate as closely as possible the native tissue. In addition, three-dimensional (3D) bioprinting has become an emerging additive manufacturing technology in tissue engineering because of its rapid prototyping capacity and the possibility of creating complex structures. This study is focused on the development of nanocellulose-alginate (NC-Alg) based bioinks for 3D bioprinting for bone regeneration. Furthermore, hydroxyapatite (HAP) and graphene oxide (GO) were incorporate as they are biocompatible, bioactive and osteoconductive materials

The main objective of three-dimensional (3D) bioprinting technology is the development of 3D constructs combining biomaterials and cells to replicate tissues and organs. Using this technique, different kinds of epitheliums can be produced in order to imitate the in vivo environment with more precision than cell cultures. Such scaffolds are usually characterized prior to evaluate cellular response upon the addition of different drugs and genetic materials. The aim of this study was to make use of 3D bioprinting technology to develop scaffolds that mimic the in vivo lung environment to evaluate the capacity of niosomes (non-viral vectors) to deliver genetic material for the treatment of cystic fibrosis (CF) genetic disorder.