A METHOD FOR TRANSPLANTATION OF THE RAT KIDNEY*

History of (micro) vascular surgery and the development of small-caliber blood vessel prostheses (with some notes on patency rates and re-endothelialization)

The historical development of vascular surgery is reviewed from ancient times (Ruphus of Ephesus, Aëtius of Amida) to recent developments (sutured anastomosis by Carrel). Attempts to anastomose blood vessels by means of nonsuturing technique, using a ring or short tube of diverse materials called prostheses, were undertaken at the start of this century and continued until shortly after World War II. With the advent of modern polymeric materials, prostheses of different types, sizes, structures, and fabrics have been used to substitute for blood vessels, both experimentally and clinically. Recently, blood vessel prostheses with small (1-1.5 mm) internal diameters became available and have been implanted experimentally. Patency rates, biophysical and structural properties, the re-endothelialization and the neointima formation of several types of microvascular prostheses are briefly reviewed.

Lung transplantation in the rat: I. Technique and survival

For immunogenetic and economical reasons, an operative technique for lung transplantation in the rat was developed. With the use of an operation microscope and 8-0, 9-0, and 10-0 sutures, the left pulmonary artery, vein, and brochus were anastomosed. The mean operation time was 4 hours; the mean graft ischemia time, 87 minutes. After frequent failures initially, due to anesthetic problems and lack of experience with microsurgical operative technique, a final peroperative survival of about 80% was obtained. Postoperative mortality approximated 50%. The main cause of postoperative death was thrombus formation at the site of an anastomosis. In a final series of 28 isogeneic transplantations, proper data for a one-month follow-up was obtained from 36% of the animals that underwent operation, a percentage comparable with initial canine pulmonary and rat renal transplantation studies. Left lung transplantation in the rat proved to be technically feasible and may provide an immunogenetically well defined and economically advantageous animal model in lung transplantation research.

[Xenogenic transplantation of aortic segments. Korrelated serological and histological investigations of the rejection mechanism]

With CDF inbred strain rats and randomly bred guinea pigs one syngenic control group and two xenogenic experimental groups were examined. The two xenogenic groups had different transplantation sites of aortic segments, the first of which was orthotoply retroperitoneal, the second heterotoply subcutanous. The following results were obtained: 1. A xenogenic vessel graft induces a massive production of antibodies after the fifth day, reaching a maximum on the 42nd day, and slowly and continuously decreasing thereafter. The tissue of the graft becomes acellular within 12 to 24h p.op. After 5 to 6 days an infiltrate appears, firstly dominated by granulocyts and monocyts and later by lymphocyts and plasmacells. Following the continuous destruction of the elastic fibres aneurysms grow. 2. The two xenogenic groups show that these two transplantation sites have no significance for the humoral response. 3. Both the progress of the antibodytiters (strong increase after the fifth day) after transplantation of aortic segments and the acute and chronical histologic changes suggest an immunological mechanism of hyperacute rejection.

[Allogenic and xenogenic aortic segmental transplants in inbred rats angiographically demonstrable vascular changes (author's transl)]

In order to make a systematic study of the significance of immunological reactions in vascular grafts, segments of abdominal aorta (4-5 mm long) were grafted into inbred rats. Four experimental combinations were used: I. syngeneic (CDF leads to CDF), II. weakly allogeneic (LEW leads to CDF), III. strongly allogeneic (BD 5 leads to CDF), IV. xenogeneic (guinea pig leads to CDF). After 100 days the gaft was macroscopically evaluated, angiographed and measured. Whereas no alterations of the vascular wall were found in group I, the degree of aneurysm formation increased significantly corresponding to the degree of histoincompatibility in the other groups: group II showed little aneurysm formation (medicum size 1.27 fold), group III more pronounced (1.71 fold) and group IV very pronounced (3.9 fold) with partial thrombosis in 3/5 of the cases. These findings are interpreted, as functional and morphological consequences of the immunogenicity of the aorta tissue. The conclusion was reached that the degree of histoincompatibility should be more carefully considered, also in vascular grafting.