3D biofabrication for tubular tissue engineering

The therapeutic replacement of diseased tubular tissue is hindered by the availability and suitability of current donor, autologous and synthetically derived protheses. Artificially created, tissue engineered, constructs have the potential to alleviate these concerns with reduced autoimmune response, high anatomical accuracy, long-term patency and growth potential. The advent of 3D bioprinting technology has further supplemented the technological toolbox, opening up new biofabrication research opportunities and expanding the therapeutic potential of the field. In this review, we highlight the challenges facing those seeking to create artificial tubular tissue with its associated complex macro- and microscopic architecture. Current biofabrication approaches, including 3D printing techniques, are reviewed and future directions suggested.

Bioprinting and in vitro characterization of alginate dialdehyde-gelatin hydrogel bio‑ink

Cell-laden cardiac patches have recently been emerging to renew cellular sources for myocardial infarction(MI,commonly know as a heart attack)repair.However,the fabrication of cell-laden patches with porous structure remains challenging due to the limitations of currently available hydrogels and existing processing techniques.The present study utilized a bioprinting technique to fabricate hydrogel patches and characterize them in terms of printability,mechanical and biological properties.Cell-laden hydrogel(or bio-ink)was formulated from alginate dialdehyde(ADA)and gelatin(GEL)to improve the printability,degradability as well as bioactivity.Five groups of hydrogel compositions were designed to investigate the influence of the oxidation degree of ADA and hydrogels concentration on the properties of printed scaffolds.ADA-GEL hydrogels have generally shown favorable for living cells(EA.hy926 cells and hybrid human umbilical vein endothelial cell line).The hydrogel with an oxidation degree of 10%and a concentration ratio of 70/30(or 10%ADA70-GEL30)demonstrated the best printability among the groups examined.Formulated hydrogels were also bioprinted with the living cells(EA.hy926),and the scaffolds printed were then subject to the cell culture for 7 days.Our results illustrate that the scaffolds bioprinted from 10%ADA70–GEL30 hydrogels had the best homogenous cell distribution and also the highest cell viability.Taken together,in the present study we synthesized a newly formulated bio-ink from ADA and GEL and for the fist time,used them to bioprint cardiac patches,which have the potential to be used in MI repair.

Bio-printing of aligned GelMa-based cell-laden structure for muscle tissue regeneration

Volumetric muscle loss(VML)is associated with a severe loss of muscle tissue that overwhelms the regenerative potential of skeletal muscles.Tissue engineering has shown promise for the treatment of VML injuries,as evidenced by various preclinical trials.The present study describes the fabrication of a cell-laden GelMa muscle construct using an in situ crosslinking(ISC)strategy to improve muscle functionality.To obtain optimal biophysical properties of the muscle construct,two UV exposure sources,UV exposure dose,and wall shear stress were evaluated using C2C12 myoblasts.Additionally,the ISC system showed a significantly higher degree of uniaxial alignment and myogenesis compared to the conventional crosslinking strategy(post-crosslinking).To evaluate the in vivo regenerative potential,muscle constructs laden with human adipose stem cells were used.The VML defect group implanted with the bio-printed muscle construct showed significant restoration of functionality and muscular volume.The data presented in this study suggest that stem cell-based therapies combined with the modified bioprinting process could potentially be effective against VML injuries.