Low molecular weight poly((D,L)-lactide-co-caprolactone) liquid inks for diluent-free DLP printing of cell culture platforms.

Digital light processing (DLP) printing offers the possibility of fabricating complex objects in a fast and reproducible manner. A main requirement for DLP printing is the use of inks with low viscosities that can flow under the printing platform in a short period of time. Its exploitation in tissue engineering applications has been centered on the use of hydrogel forming materials diluted in aqueous solutions or the use of polyesters in combination with diluents and heating platforms that aid in the reduction of their viscosity. The use of diluents, however, modifies the mechanical properties and reduces the shape fidelity of the printed objects and, the use of heating platforms results in vats with heterogeneous temperatures and ink viscosities. Here, we report on the synthesis of a library of methacrylated low molecular weight (<3000 g mol-1) homopolymers ((P(D,L)LA and PCL) and copolymers (P((D,L)LA-co-CL)) of 2- and 3-arms based on (D,L)-lactide and ε-caprolactone. The resulting inks possessed low viscosity that made them printable in the absence of diluents and heating elements. DLP printing of cubical and cylindrical patterns resulted in objects with a higher shape fidelity than their counterparts fabricated using diluents and with printed features on the order of 300 µm. The printed materials were biocompatible and supported the growth of human mesenchymal stem cells (hMSCs). Moreover, the variations in the composition resulted in polymers that enabled the attachment of hMSCs to different extents, leading to the formation of well-adhered cell monolayers or loosely adhered cell aggregates.

Recent advances in gelatin-based therapeutics.

INTRODUCTION: Biomaterials have provided a wide range of exciting opportunities in tissue engineering and regenerative medicine. Gelatin, a collagen-derived natural biopolymer, has been extensively used in regenerative medicine applications over the years, due to its cell-responsive properties and the capacity to deliver a wide range of biomolecules. AREAS COVERED: The most relevant properties of gelatin as biomaterial are presented together with its main therapeutic applications. The latter includes drug delivery systems, tissue engineering approaches, potential uses as ink for 3D/4D Bioprinting, and its relevance in organ-on-a-chip platforms. EXPERT OPINION: Advances in polymer chemistry, mechanobiology, imaging technologies, and 3D biofabrication techniques have expanded the application of gelatin in multiple biomedical research applications ranging from bone and cartilage tissue engineering, to wound healing and anti-cancer therapy. Here, we highlight the latest advances in gelatin-based approaches within the fields of biomaterial-based drug delivery and tissue engineering together with some of the most relevant challenges and limitations.

Advances in stem cell therapy for cartilage regeneration in osteoarthritis.

INTRODUCTION: Osteoarthritis (OA) is a progressive joint disease that compromises the structural integrity of cartilage tissue. Conventional treatments based on medication or surgery are nowadays inefficient and cell-based therapy has emerged as one of the most promising methods for cartilage regeneration. The first therapy developed for cartilage defects was autologous chondrocyte implantation, but in the last few decades stem cells (SCs) from different sources have been proposed as a possible alternative for OA. AREAS COVERED: SC sources and available delivery procedures (scaffolds/hydrogels) are presented, along with the main issues arisen in this regard. Thereafter, preclinical and clinical trials performed in recent years are reviewed in order to take a glance toward the potential benefits that such therapies could deliver to the patients. EXPERT OPINION: SCs have proven their potential and safety for OA treatment. Nevertheless, there are still many questions to be resolved before their widespread used in clinical practice, such as the treatment mechanism, the best cell source, the most appropriate processing method, the most effective dose and delivery procedure, and their efficacy. In this sense, long-term follow-up and larger randomized controlled trials utilizing standardized and established outcome scores are mandatory to make objective conclusions.

Active naringin-chitosan films: impact of UV irradiation.

Bioactive citrus extract-chitosan films were prepared through solvent casting-evaporation method. The impact of near UV irradiation was studied to reach a better understanding of the film behavior. The antimicrobial activity of films against Listeria innocua was maintained after UV irradiation. To study the interaction between chitosan and citrus extract components, naringin (main component) was selected as the model compound. UV treatment caused modifications of the flavanone regardless of the solvent used for its dissolution, depending on the concentration of naringin in the film: the greater the concentration the lower the modification. DSC results suggested cross-links due to UV irradiation and interactions between naringin and chitosan. This was confirmed by a decrease in the naringin release from the irradiated samples. Naringin- and citrus extract-chitosan films showed an increased absorbance in the UV region compared to pure chitosan films, showing potentiality for decreasing the lipid oxidation induced by UV light in foodstuffs.