Immunoisolated effect of xenografts of microencapsulated human chromaffin cells in rats

Jiheng CHEN; Maoyuan YANG; Jiyong LI; Xianzhong LIN; Haosheng BI

ABSTRACT

BACKGROUND:

Based on previous technique prepared for encapsulating living cells with alginate-polysine- alginate (APA) microcapsules, it has been confirmed that microencapsulated chromaffin cells have good analgesic effects. The immunoisolated effects of such microcapsule materials need to be evaluated.

OBJECTIVE:

This study aimed to investigate the immunological rejections of APA microencapsulated chromaffin cells transplanted into rat anterior chamber of eyes and tendon of feet, and to evaluate the immunoisolated effect of microencapsulation.

DESIGN:

A randomized controlled animal experiment.

SETTING:

Department of Anesthesiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology.MATERIALS Forty-eight female SD rats, with the age of 3 months, were provided by the Laboratory Animal Center, Tongji Medical College, Huazhong University of Science and Technology. The protocol was carried out in accordance with ethical guidelines for the use and care of animals. Alginate and polylysine used in the experiment were the products of Sigma Company, USA. Microcapsule generator was gifted by Germany.

METHODS:

This study was performed at the Department of Anesthesiology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology from September 2002 to September 2003. Suprarenal medulla was taken from 6 healthy adult cadavers of brain death. After isolated, digested and cultured, suprarenal medulla was prepared into chromaffin cell suspension. Written informed consents were obtained from the family members of donors, and the protocol was given approval by the Ethics Committee of the hospital. Empty microcapsules and microencapsulated cells were prepared by APA. The 48 rats were randomly divided into the human chromaffin cell (HCC) group, the empty microcapsule group and the microencapsulated HCC (ME-HCC) group. In each group, there were two transplanted regions of anterior chamber of eyes and tendon of feet, with 8 rats used for each region. Each rat in the HCC group was perfused 2×1010 L-1 cell suspension into the anterior chamber of eyes and tendon of feet. Those in the empty microcapsule group and the ME-HCC group were perfused 100 empty capsules and ME-HCCs (100 microcapsules, 400-500 HCCs per microcapsule) into the same regions, respectively. MAIN OUTCOME

MEASURES:

On day 7 after transplantation, serum interleukin (IL)-2 level was determined by ELISA. Serum IgG and IgM levels were determined with a laser turbidimeter. On day 28 after transplantation, rat right eyeball and left feet were harvested, routinely sliced and stained by haematoxylin-eosin (HE). Histo-morphological structure was observed under a 40×light microscope.

RESULTS:

Forty-eight rats were included in the final analysis. Serum IL-2, IgG and IgM levels were significantly lower in the empty microcapsule group and ME-HCC group than in the HCC group (t=8.544-21.64, P < 0.01). A lot of lymphocyte and neutrophile infiltration could be found in the anterior chamber of eyes and tendon of feet of rats in the HCC group, but a little seen in that of the empty microcapsule group and ME-HCC group.

CONCLUSION:

APA microencapsulation has an effective immunoisolated effect on immunological rejection due to its good biocompatibility and mechanical stability.