Experimental Study Of The Transplantation Of Alginate-Chitosan-Alginate Encapsulated Bovine Chromaffin Cells For Analgesia

Objective: Pain is the common symptom of most patients. Chronic pain not only influences the life quality of the patients, but also heavily burdens the families and the society. Chronic intractable pains include rheumatic pain, neural injury related pain and terminate oncologic pain. pain of oncologic origin has become a social and medical problem in the world, because of the high incidence and mortality of malignant tumors. Traditional medication for pain cannot satisfactorily cure chronic pain. Cell/tissue transplantation is a new therapy that can solve the problem of the unsatisfactory cure effect and the potential side effects of drugs. The biggest issue of Cell/tissue transplantation is transplant rejection. The technology of immunoisolation developed in 1970s is one of the main methods to solve the problem of rejection. In this study, we adopted natural polymers to fabricate alginate-chitosan-alginate(ACA)microcapsules. We tested the morphology, membrane strength, permeability, biocompatibility and culture properties of ACA capsules fabricated with chitosan of different molecular weights and in different membrane-forming time in order to optimize the materials and fabricating conditions of microcapsules for transplantation. In addition, we used the hot plate to test the analgesia and immunoprotection effect of ACA encapsulated bovine chromaffin cells on mice. Methods: 1. Electrostatic droplet technique was adopted to fabricate ACA microcapsules with chitosan of different molecular weights and in different membrane-forming time. 2. The sodium citrate liquidation membrane strength test was adopted to test the membrane strength of ACA microcapsules fabricated in different conditions. 3. Ultraviolet spectrophotometry was adopted to test the permeability and immunoisolation effect of ACA microcapsules fabricated in different conditions. 4. Primary bovine chromaffin cell was cultured in the presence of chitosan in order to test the in vitro biocompatibility of chitosan. Microencapsulated cell culture was adopted to test the in vitro biocompatibility of ACA. Mice peritoneal transplantation was adopted to test the in vivo biocompatibility of ACA. 5. Mouse peritoneal transplantation test and hot plate test were adopted to test the analgesia effect of microencapsulated bovine chromaffin cells and the immunoprotection of ACA, the control groups in this test were alginate-polylysine-alginate (APA) microencapsuled bovine chromaffin cells group,unencapsulated bovine chromaffin cells group,empty ACA microcapsules group and the normal saline .Results: 1. ACA microcapsules fabricated by electrostatic droplet technique were spherical with even particle diameters and smooth surfaces. 2. The test of the membrane strength of ACA microcapsules: Sodium citrate treated ACA microcapsules swelled with time. All the microcapsules swelled rapidly at the first stage and they swelled more slowly at later stages. (1) The molecular weight of chitosan influences the membrane strength of ACA microcapsules. Microcapsules fabricated with chitosan of low molecular weight swelled later than microcapsules fabricated with chitosan of higher molecular weight and their swelling velocity was also higher at each time point. (2) Membrane-forming time influences the membrane strength of ACA microcapsules. Microcapsules fabricated in short membrane-forming time swelled earlier than microcapsules fabricated in longer membrane-forming time and their swelling velocity was higher at each time point. 3. The permeability test of ACA microcapsules. The solute and fabricating conditions affect the permeability of ACA microcapsules. (1) The permeability of ACA microcapsules for proteins of different molecular weight: ACA microcapsules fabricated with chitosan of different molecular weight and in different membrane-forming time did not allow high molecular γ-globulin to permeate through, while they allow the lower molecular BSA and pepsin to permeate through. The permeability velocity of pepsin was the fastest. (2) The molecular weight of chitosan influ...