Polycaprolactone Combined with Platelet-Rich Fibrin and Adipose-Derived Stem Cells for Endothelialized Small Caliber Vascular Graft in Bioreactor System

Abstract

According to the report published from World Health Organization (WHO) cardiovascular diseases (CVDs) rank number one the cause of death globally Moreover there were estimated 17 5 million people died from CVDs in 2012 The patients suffering serious vascular disease have to receive the vascular graft surgery There are two common vessel substitute resources one is autologous vessels and the other is artificial vascular graft Comparing to autologous vessel the artificial vessel has some advantages such as low-cost and easy to manufacture However the patency of small caliber vascular graft implantation surgery is only near 50 % within 3 years It is because of lacking the endothelium layer that the artificial graft cannot regulate the vascular physiology conditions Further it leads to thrombosis even intimal hyperplasia In the recent researches of vascular tissue engineering fabricating an endothelial layer vascular graft is a major issue In this study adipose-derived stem cells (ADSCs) were seeded on the biodegradable PCL which was modified with platelet-rich fibrin (PRF) scaffold And this scaffold was cultured in the dynamic conditions to form an endothelium vascular graft In the part I of the study 2 mm of the inner diameter 4 mm of the outer diameter and 5 cm of the length PCL scaffold was fabricated by salt-leaching method The porosity of the scaffold was about 75 % on the other hand the pore size was around 150~250um Then the scaffold was immersed in the mixed solution of ADSCs suspension and platelet-rich plasma (PRP) overnight The scaffold would be cultured in the static for 3 weeks In the result it showed that adding PRF can increase the cell attachment on the scaffold which was modified the hydrophobic problem of polycaprolactone (PCL) In addition the growth factors in the PRF not only enhanced ADSCs proliferation but also induced the endothelial cells differentiation from ADSCs In the part II of the study the ECs containing PRF/PCL scaffold was cultured in the dynamic condition for a week The dynamic condition was made of the bioreactor system with two different fluid waveform laminar flow and pulsatile flow To find out the better culture environment for the vascular scaffold there were two kinds of designed groups the static culture and the dynamic culture which included the laminar flow condition and the pulsatile flow condition In the result comparing to the static condition the scaffold cultured in the dynamic condition showed more type I collagen and higher Young’s modulus On the other hand the ECM formation and the burst pressure were increased in the groups of the pulsatile condition Moreover the ECs aligned at the luminal side of scaffold after receiving the pulsatile stimulation In summary the combination of PRF PCL vascular scaffold and ADSCs were successful to form the endothelial layer in the inner surface and the ECM within the scaffold Finally the vascular scaffold became structural and functional better through the mechanical stimulation from bioreactor system

Date of Award	2016 Sept 5
Original language	English
Supervisor	Ming-Long Yeh (Supervisor)