Perfusion directed 3D mineral formation within cell-laden hydrogels

Abstract

Despite the promise of stem cell engineering and the new advances in bioprinting technologies, one of the major challenges in the manufacturing of large scale bone tissue scaffolds is the inability to perfuse nutrients throughout thick constructs. Here, we report a scalable method to create thick, perfusable bone constructs using a combination of cell-laden hydrogels and a 3D printed sacrificial polymer. Osteoblast-like Saos-2 cells were encapsulated within a gelatin methacrylate (GelMA) hydrogel and 3D printed polyvinyl alcohol pipes were used to create perfusable channels. A custom-built bioreactor was used to perfuse osteogenic media directly through the channels in order to induce mineral deposition which was subsequently quantified via micro-CT. Histological staining was used to verify mineral deposition around the perfused channels, while COMSOL modeling was used to simulate oxygen diffusion between adjacent channels. This information was used to design a scaled-up construct containing a 3D array of perfusable channels within cell-laden GelMA. Progressive matrix mineralization was observed by cells surrounding perfused channels as opposed to random mineral deposition in static constructs. Micro-CT confirmed that there was a direct relationship between channel mineralization within perfused constructs and time within the bioreactor. Furthermore, the scalable method presented in this work serves as a model on how large-scale bone tissue replacement constructs could be made using commonly available 3D printers, sacrificial materials, and hydrogels.

Hybrid Laser Printing of 3D, Multiscale, Multimaterial Hydrogel Structures

“…Gelatin Methacrylate (GelMA) macromer was synthesized as described previously . Briefly, 200 mL Dulbecco's phosphate buffered saline (DPBS, Gibco) was heated to 40 °C, and was used to dissolve 10 g of porcine skin gelatin (Sigma Aldrich, St. Louis, MO).…”

Photochemically crosslinked cell‐laden methacrylated collagen hydrogels with high cell viability and functionality

“…The photopolymerization process is enabled via a photoinitiator which is a light-sensitive reagent that when exposed to a specific light wavelength will dissociate into free radicals that in turn induce the photopolymerization of the hydrogel. 3 While many different types of photoinitiators have been investigated, [4][5][6][7][8] Irgacure 2959 (I2959) is the most widely used [9][10][11] due to its high free radical generation efficiency and relatively higher water solubility. 3 However, there are concerns related to the cytotoxicity of the free radicals generated using I2959 for fast dividing cell lines.…”

Computational fluid dynamic analysis of bioprinted self‐supporting perfused tissue models

“…There were, in effect, three microchannel diameters analyzed in the SSuPer tissue used as proof of concept. The fact that only tissue surrounding the smallest diameter channel exhibited mineralization supports the concept that perfusion induced shear stress can modulate osteogenesis (Sawyer et al, ).…”