Biological perspectives and current biofabrication strategies in osteochondral tissue engineering

From Springer Nature via Jisc Publications RouterHistory: received 2019-09-26, accepted 2020-06-29, registration 2020-06-29, pub-electronic 2020-07-09, online 2020-07-09, pub-print 2020-12Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; doi: http://dx.doi.org/10.13039/501100000266; Grant(s): EP/L014904/1Funder: Fundação para a Ciência e a Tecnologia; doi: http://dx.doi.org/10.13039/501100001871; Grant(s): PTDC/MEC-GIN/29232/2017, 0245_IBEROS_1_EAbstract: Articular cartilage and the underlying subchondral bone are crucial in human movement and when damaged through disease or trauma impacts severely on quality of life. Cartilage has a limited regenerative capacity due to its avascular composition and current therapeutic interventions have limited efficacy. With a rapidly ageing population globally, the numbers of patients requiring therapy for osteochondral disorders is rising, leading to increasing pressures on healthcare systems. Research into novel therapies using tissue engineering has become a priority. However, rational design of biomimetic and clinically effective tissue constructs requires basic understanding of osteochondral biological composition, structure, and mechanical properties. Furthermore, consideration of material design, scaffold architecture, and biofabrication strategies, is needed to assist in the development of tissue engineering therapies enabling successful translation into the clinical arena. This review provides a starting point for any researcher investigating tissue engineering for osteochondral applications. An overview of biological properties of osteochondral tissue, current clinical practices, the role of tissue engineering and biofabrication, and key challenges associated with new treatments is provided. Developing precisely engineered tissue constructs with mechanical and phenotypic stability is the goal. Future work should focus on multi-stimulatory environments, long-term studies to determine phenotypic alterations and tissue formation, and the development of novel bioreactor systems that can more accurately resemble the in vivo environment

Hybrid PCL/hydrogel scaffold fabrication and in-process plasma treatment using PABS

A key challenge in tissue engineering is the fabrication of synthetic scaffolds with adequate chemical, physical and biological cues. This paper describes a novel plasma-assisted bioextrusion system (PABS) to produce functional-gradient scaffolds. It comprises two pressureassisted and a screw-assisted printing head and plasma jets. Hybrid scaffolds consisting of a synthetic biopolymer and a natural hydrogel, and full-layer N2 plasma modified polymeric scaffolds were produced to assess the system. Water contact angle and in vitro biological tests confirm that the plasma modification alters the hydrophilicity properties of synthetic polymers and promotes proliferation of cells, leading to homogeneous cell colonization. It is also demonstrated the capability to produce multi-material structures. The results suggest that PABS is a promising system for the fabrication of functionally-graded scaffolds.Published versio

Characterisation of cross-linked hydrogel structures for cartilage applications

Alginate is a biocompatible natural hydrogel being explored to create cartilage replacements either on its own or as part of a composite material. Bioprinting technologies based on photopolymerization principles are being used make such structures. In this paper, the effect of functionalization time on the mechanical morphology, swelling and degradation characterization of cross-linked alginate hydrogel is investigated. Alginate, chemically-modified with methacrylate groups and different reaction times is considered, by dissolving functionalized alginate with 1.5% photoinitiator solution and crosslinked by ultraviolet (UV) light (8 mW/cm2). Results show that by increasing the functionalization time, it was possible to obtain alginate material with a high level of unsaturation resulting in a less porous structure with high mechanical properties and a reduction of swelling. The influence of increasing the prepolymer concentration, reaction time and the amount of photoinitiator (PI) on mechanical and biomimetic properties of resulting hydrogels led to increased mechanical stiffness when measured at 10% strain. The swelling ratio of Photocrosslinked alginate hydrogels was studied and initial findings link this behavior to functionalization reaction time.Published versio