Scientists in China say they have taken the first step toward a new way of treating gastric wounds by using a microrobot combined with the new concept of “in situ in vivo bioprinting” to carry out tissue repair inside the body. Their study, “Preliminary engineering for in situ in vivo bioprinting: a novel micro bioprinting platform for in situ in vivo bioprinting at a gastric wound site”, published in Biofabrication, establishes proof-of-concept for this new method in the field of bioprinting they add.

“We first proposed the concept of in situ in vivo bioprinting in order to address the existing deficiencies in conventional bioprinting. Herein we verified this concept taking the case of the treatment for gastric wall injury and presented this work as a preliminary step towards a new method in the field of bioprinting,” write the investigators.

“In this study, a micro bioprinting platform which can be installed to an endoscope was developed to enter the human body and process bioprinting. Printed circuit micro-electro-mechanical-system techniques were used in the design and fabrication of the platform. Control system with high accuracy was developed and performance tests were carried out to verify the feasibility of the platform.

“The 2-layer tissue scaffolds were printed in a stomach model. Gelatin–alginate hydrogels with human gastric epithelial cells and human gastric smooth muscle cells were used as bioinks to mimic the anatomical structure of a stomach. A 10 d cell culture showed that printed cells remained a high viability and a steady proliferation, which indicated good biological function of cells in printed tissue scaffolds. This work presents an innovative advance not only in the field of bioprinting but also in the clinical sciences.”

“Gastric wall injury is a common problem in the digestive tract, and about 12 percent of the world’s population suffer from it to varying degrees,” notes Tao Xu, PhD, from Tsinghua University in Beijing and co-author of the study. “Bioprinting, delivering new cells directly to the wound site to repair the tissue, offers a potentially useful way to treat the problem. The difficulty is that current bioprinting technology focuses on external sites. Bioprinters are normally quite large, and cannot be applied to inner tissue repair without invasive surgery to give enough room for the printing operation. To overcome this, we developed a microrobot that enters the body via an endoscope to carry out tissue repair inside the body.”

The bioprinting platform Xu and his PhD student Wenxiang Zhao developed, is a Delta robot composed of a fixed base, moving platform, and three identical kinematic chains. To be as minimally-invasive as possible, it can fold itself down when entering the patients’ body, then unfold before beginning the bioprinting operation.

“We tested the system in two ways,” said Zhao. “First, with a biological model of a human stomach and an endoscope, to mimic the insertion and printing operation elements of the process. Second, we carried out a bioprinting test in a cell culture dish to test how effective the device was at bioprinting viable cells and repairing wounds.”

“Both tests showed promising results. A 10-day cell culture showed that printed cells remained at a high viability and a steady proliferation, which indicated good biological function of the cells in printed tissue scaffolds.”

“Although only a first step, this study has verified the feasibility of this concept for treatment for gastric wall injuries,” according to Xu. “More work is needed to bring it to full realization, including reducing the size of the bioprinting platform and developing bioinks. Our future studies will concentrate on these areas.”

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