The study of 3D printing technology in producing tissue regeneration scaffold for urological diseases and clinical surgery application

Jia-En Chen1,4, Han-Yen Hu2, Dah-Shyong Yu3,4

Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan1

Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan2
Division of Urology Department of Surgery, Tri-Service General Hospital, National Defense Medical Center,Taipei,Taiwan3

Medical 3D Printing Center, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan4

Graduate Institute of Automation and Control, National Taiwan University of Science and Technology, Taipei, Taiwan5

Purpose: The inception of 3D printing technologies will enable provisioning of customized or patient-specific healthcare; accelerate medical digitalization; and kick-start revolutionary advancement of medical science. In 2012 The Economist has boldly predicted that 3D printing will be the critical technology to usher in the 3rd wave of industrial revolution. Via 3D printing technologies, not only can we significantly improve surgical qualities and patient outcomes, we may also be able to print implantable organs in the future, when coupled with breakthrough advancements of regenerative medicine. Clinically, tissue reconstruction is needed in patients with a urethral and ureteral injury with extended segment defects. However, there is no customized platform and suitable bio-compatibility materials to produce the tissue regeneration vehicle currently. We hope this customized scaffold could be a useful replacement material in tissue regeneration for urological trauma patients. Electrospinning (ES) system is a new nanofiber process technology in recent years. It can directly and quickly spin the material into nanofibers, improve the specific surface area, porosity and micro/nano-scale pore structure. Applied in different fields; 3D printing technology can provide uniform and customized brackets. Our study chooses highly bio-compatibility materials, silk fibroin (SF) and polycaprolactone (PCL) as bio-materials scaffolds respectively. Comparing the differences in physicochemical properties and biocompatibility of bio-scaffolds prepared by ES and 3D printing combined with electrospinning (3D-ES).

Materials and Methods: SF powder was made from dissolved cocoons, then extracted by dialysis and lyophilized before the study. ES or self-designed 3D-ES platform generated various ratios of PCL and SF nanofiber in formic acid. The physical and biological characteristics were assayed by SEM, degradation test, tension test and cell attachment assay of fibroblasts and urothelial cells on various nanofibers of PCL-SF. The ex vivo resected ureteral tissue was anastomosed with the PCL-SF Scaffolds and cultured in ex vivo bath for two weeks. The cellular growth on the scaffold was observed microscopically by HE stain. In the New Zealand white rabbit model, we performed a 1/5 ratio replacement of the unilateral ureter. After six and seven weeks, the animals were sacrificed and were taken out the scaffold for tissue sectioning, and HE and Masson staining observed the attachment growth.

Results: In the physical assay, both the diameter and size of nanofiber holes were increased in the PCL-SF scaffold when the proportion of SF is increased. There is no difference for degradation rate under cell culture medium soaking for eight weeks which was 10%. The tensile strength of PCL-SF nanofibers increased when the PCL ratio increased. Typical spectrum peaks for PCL and SF were observed in the spectra of PCL/SF blends. MTT result indicates that the incorporation of SF into PCL was beneficial for cell proliferation and parallel to the percentage of SF ratio and 4:6 of PCL-SF scaffold is the best ratio for cellular growth. Higher cellular proliferation was seen in 3D-ES 4:6 PCL-SF scaffolds than ES 4:6 PCL-SF scaffolds due to the increased diameter of nanofibers and size of holes. The PCL-SF scaffold anastomosis in ex vivo bath showed cellular growth stably along the structure for two weeks, and most of the cells grow along the outboard. In the animal model, after 6 and 7 weeks, different cells can be observed to develop along the outboard of the scaffold, from the lumen outward: Mucosa, Submucosa, muscular layer and the serosa layer, mucosal layer growth in the scaffold inner edge of close kidney sild, Mucosa and muscular layer growth in the scaffold inner edge of close bladder sild, However, in the middle of the inner side of the scaffold, the cells had not grown and attached for 7 weeks.

Conclusions: In our study, 3D-ES produced 4:6 PCL-SF nanofiber scaffolds which suitable for cell tissue growth and achieved the purpose of ureteral reconstruction in animal experiments so that this new vector can be used as clinical urinary tract system organization in future.


    2019-01-03 15:56:12
    2019-01-03 15:59:09
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