Abstract： Objective To observe the immune separation effects of micro-capsules from alginate-polylysine-alginate(APA)in the rat cerebral transplantation of bovine chromaffin cell(BCC)grafts.Methods Microencapsulated BCC,non-microencapsulated BCC or empty microencapsulated BCC were grafted into the striatum of the hemiparkinsonian disease(PD)-like rats respectively.The abnormal rotational behavior induced by apomorphine was observed in the rats after operation.At the end of experiments the rats were killed and transcardially perfused with 300 ml normal saline.The brains were removed and frozen sections were cut in coronal plane on a freezing microtome.The BCC grafts and micro-capsules in the brains were observed under a fluorescent microscope after SPG staining and HE staining.Results The changes in abnormal behavior of PD-like rats in empty microencapsulated graft group were not significant in 10 months (P>0.05).Among the 16 PD-like rats in non-microencapsulated graft group,9 rats had an improvement of abnormal rotational behavior one week after transplantation,with the rotations being decreased to 44.0%～60.9% of pregrafting in non-microencapsulated BCC graft group(P<0.01).At the 10th month of postgrafting there were a large number of survival BCC in the host striatum with only minimum host reaction in microencapsulated BCC graft grotip.On the 6th month of postgrafting there was some survival BCC in the host corpus striatum accompanied by inflammatory response in non-microencapsulated BCC graft group.There was a significant difference in apomorphine-induced rotational behavior between microencapsulated BCC graft group and non-microencapsulated BCC graft group(P<0.01).Conclusion Transplantation of BCC into brain can improve the abnormal rotational behavior in PD-like rats,which was correlated with the SUrvival of BCC in the host brain.The micro-capsules from APA can decrease the host irnrnune response to the heterogenic BCC grafts.