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The development of 3D bioprinting technology has provided a new direction for the replacement of organs or tissues and the development of drug testing models. Testing cell adhesion, proliferation, and differentiation in different printed scaffolds for creating functional 3D bio-printed structures provides the possibility of establishing a patient-specific in vitro model for neurodegenerative diseases. This thesis aims to establish a 3D bio-printed spinal cord model for drug research of ALS by exploring the factors affecting cell adhesion, growth, and differentiation in different hydrogels, and the suitable printing conditions.

In Paper I, we compared the adhesion and cell survival rates of BCs on the surfaces of the scaffolds with different stiffness and different chemical covering substracts and found the effects of physical and chemical factors for cell adhesion, proliferation, and differentiation through comparison, which can be used as a reference for exploring the conditions for further 3D printing mixing with cells inside. 

In Paper II, gelatin-based hydrogel was selected as the main material for printing the scaffold. By testing the survival rate of BCs in the different concentrations of gelatin with different concentrations of crosslinker, we selected a protocol that is suitable for cell viability, cell differentiation, and bioprintability. Unfortunately, when this protocol is applied to hiPSCs, it can obtain the viability of cells after printing, but cell differentiation was only observed on the surface of the scaffolds since cells in the middle of the printed structure lack contact with the surrounding culture medium.

Paper III showed that BCs attracted endothelial cells sprouting from aortic rings in their co-cultured 3D-printed scaffolds and guided the migration direction of endothelial cells. Also, after implantation at the injury DRTZ, they helped with vascularization by increasing the blood vessel volume and vessel diameters.

In Paper IV, we improved the protocol from Paper II for hiPSCs-derived MNs by reducing the concentration of gelatin and adding MSP loaded with cintrofin and gliafin. Two printable methods that could keep the printed structures during culturing were tested, and one was chosen for further printing based on cell viability during bio-ink preparation. A lower concentration of gelatin helped with getting better access to the surrounding culture medium and achieving motor neuron differentiation inside the scaffolds.