Fetal rhesus monkey model of obstructive renal dysplasia.

BACKGROUND: Disorders of kidney development represent a major cause of renal failure and end-stage renal disease in the pediatric population. To understand further the prenatal pathogenesis of obstructive renal dysplasia, a fetal monkey model was developed using ultrasound-guided techniques. METHODS: Ureteropelvic obstruction (N = 13) was induced during the early or late second trimester by the injection of purified guluronic alginate spheres. All fetuses were monitored sonographically, and then fetal tissues were removed at varying time points during the second and third trimesters. RESULTS: There was no evidence of oligohydramnios during the course of gestation, and the obstructed kidneys were typically progressively smaller than the contralateral (nonobstructed) kidneys when monitored sonographically over time. Obstructed kidneys displayed most features of renal dysplasia, including numerous cortical cysts of various sizes derived predominantly from collecting ducts and glomeruli. Mesenchymal changes included expansion of both the cortical and medullary interstitium, as well as mesenchymal-myocyte transformation, expressed as pericystic and peritubular fibromuscular collar formation. An important feature of this model was the disruption of normal glomerular development and architecture, associated with significant podocyte apoptosis, evident as early as the prevascularized S-shaped nephron. As in other models, collecting duct cell apoptosis was apparent, particularly in areas of cyst formation and cellular atrophy. CONCLUSIONS: These results demonstrate the importance of this nonhuman primate model for exploring the pathophysiology of congenital obstructive uropathy and highlight the potential role of podocyte injury in determining long-term renal function associated with this condition.

Studies in fetal wound healing: III. Early deposition of fibronectin distinguishes fetal from adult wound healing.

Wound healing in the fetus proceeds through a series of steps that differ in the fetus and the adult. At each phase of this complex process, there is signaling between the tissue cells and the wound microenvironment, signals that are mediated by and through the extracellular matrix. We postulate that these signals occur earlier in fetal wounds, resulting in more rapid repair. To investigate this, we compared the first 24 hours of wound healing in the rabbit fetus and adult, using antibodies against key extracellular matrix macromolecular components: laminin, fibronectin, and type-specific collagens I, III, IV, and V. Fibronectin was the first matrix component to be deposited, and was visualized as early as four hours after fetal wounding and 12 hours after adult wounding. There was no evidence of new laminin or collagen deposition in either the fetal or adult wounds at any time point examined. The early deposition of fibronectin, a matrix adhesion molecule that provides a scaffolding for epithelial migration, may underlie the rapid reepithelialization observed in fetal wounds.

Pretreatment with donor-specific blood transfusions in related recipients with high MLC.

Pretreatment with deliberate DST has not resulted in hyperacute or irreversible rejection in patients receiving kidneys after negative donor-specific crossmatches, but has afforded immunologically disparate related recipients enhanced opportunity at successful transplantation. Additionally, with a post-transplant course paralleling that of HLA-identical siblings, high-dose immunosuppressive therapy for rejection has been spared in many recipients. Transplantation, however, proved unsuccessful in a patient receiving a kidney from his positive B-warm crossmatch blood donor in a protocol departure. This case experience and subsequent antibody studies have reconfirmed our initially established criterion of not proceeding with transplantation against a persistently positive B-warm donor-specific crossmatch. By pursuing the initially established DST protocol, it appears that a potentially unsuccessful living related transplant can be avoided, while the transplants actually performed have enhanced prospects of success. The nature of the various immunologic responses in this patient population remain to be more clearly defined.

Analysis of costs and outcomes of renal transplantation at one center. Its implications.

A cost increase of more than 900% for medical services to dialysis patients and transplant recipients has been projected during the decade 1974 to 1984. To evaluate the role of renal transplantation in the End-Stage Renal Disease Program, we analyzed direct costs and patient outcomes in 466 consecutive transplants at our center. A successful transplant from either a living related or cadaver donor cost less than +7,000 per year for two years of graft function. The cost of transplants rejected during the second year also proved cost-effective when compared with the yearly costs of maintenance-facility hemodialysis. Patient survival was 100% at two years for recipients of a transplant from a living related donor and 84% at two years for recipients of a transplant from a cadaver. Renal transplantation can reduce the rising costs for end-stage renal disease patient care, without reducing life expectancy.

Macrophage-T cell interactions in the Con A induction of human suppressive T cells.

Macrophage-T interactions are required for the Con A-induced generation of human Ts capable of inhibiting PHA-induced blastogenesis among autologous PBMC. Con A treatment of adherent cell-depleted PBMC, or PBMC recovered after a 7-day incubation in FCS, failed to generate Ts. Addition of adherent cells to either of these populations restored Con A inducible Ts. Discontinuous density gradient fractionation of adherent cells demonstrated that the required accessory cell was a low density macrophage bearing the human equivalent of murine Ia.

Immunologic factors determining survival of cadaver-kidney transplants. The effect of HLA serotyping, cytotoxic antibodies and blood transfusions on graft survival.

We assessed immunologic factors determining graft survival in 510 recipients of primary cadaver allografts at one center. The degree of HLA match grade did not directly affect graft survival (54 per cent in no-antigen match, and 42 per cent in three-antigen match, at two years). There was no correlation between the HLA match grade and the degree of stimulation of the mixed lymphocyte culture. Patients receiving more than five blood transfusions had a significantly better graft survival than nontransfused recipients (52 versus 23 per cent, respectively, at two years, P less than 0.001). The beneficial effect of transfusions was noted whether or not lymphocytotoxic antibodies were produced, provided adequate screening was performed before transplantation. Transfusions did not alter the degree of stimulation in the mixed lymphocyte culture. More liberal use of transfusions and frequent screening for cytotoxic antibodies would probably result in more effective cadaver-kidney transplantation.

A ten year experience with cadaver kidney preservation using cryoprecipitated plasma.

Between August 1967 and January 1977, 699 cadaver kidneys were preserved and transplanted in our hospital after continuous perfusion with cryoprecipitated plasma. Overall graft survival of primary transplants was 55 +/- 2 per cent at one year and 41 +/- 2 per cent at four years. The results with ninety-six second transplants were similar. The number of HLA antigens shared and the duration of preservation did not influence graft survival. Patient survival among 426 cadaver graft recipients since September 1972, when lower dose immunosuppression was started, was 91 +/- 1 per cent at one year and 84 +/- 2 per cent at four years, significantly better than survival before then. Survival of fifty-two recipients of cadaver retransplants since September 1972 was 86 +/- 5 per cent at one year and 86 +/- 5 per cent at four years, which was better than before. The incidence of posttransplantation dialysis was 30 per cent and did not correlate with the length of preservation. Primary wound infections, primary ureteral extravasation, and vascular complications each occurred with an incidence of 1.1 per cent or less in patients treated with lower dose immunosuppression. Only four kidneys were lost because of complications, and in no instance was the need for transplant nephrectomy directly related to the method of preservation. Perfusion preservation with cryoprecipitated plasma gives excellent results compared with alternative methods.

The impact of 1,000 renal transplants at one center.

A large, comprehensive renal transplant program has a major impact not only on patient care, but also on the medical center itself and the larger community. The program at this center has advanced from 15 transplants in 1964 to 141 transplants in 1976. Fifty-nine per cent of patients transplanted have functioning kidneys at this time, including 76 children. Rehabilitation was equal to prerenal disease level in 91% of 169 recipients who lived five years with a functioning graft. Basic research in such diverse areas as renal preservation and immunology, as well as clinical research in optimum immunosuppressive therapy, resulted in significant contributions. Refinement of the mixed lymphocyte culture improved living-related graft survival at two years: 100% for HLA-identical and 91% for non-HLA-identical grafts, compared to 66% reported by the Transplant Registry for the combined group. Modification of immunosuppression improved patient survival at two years: 100% and 86% for recipients of living-related and cadaver grafts, respectively, compared to 83% and 65% reported by the Transplant Registry. The complexity of care of the patient with end-stage renal failure has required active interaction between transplant surgeons and almost every major specialty. The vast clinical material has been a great asset for training transplant surgeons, nephrologists, fellows and residents of multiple specialties, and medical students. The medical center's relationship with communities within a 250 mile radius has been strengthened, as reflected in patient referrals and the development of a multi-community-supported organ procurement system, which has allowed us to perform over 100 cadaver transplants per year for the past three years. Thus the performance of 1,000 renal transplants at this center has resulted not only in rehabilitation of many renal failure patients, but also in expanded and improved research and teaching capabilities, bringing support from multiple medical disciplines and the general community.

Urological complications of renal transplantation can be prevented or controlled.

Our incidence of urological complications in 860 consecutive renal transplants in 3.4 per cent. A further reduction in incidence is demonstrated in the most recent 250 transplants of this series. Urological complications have been kept to a minimum by strict adherence to certain principles in donor nephrectomy, management of multiple and small arteries, and the technique of graft implantation. When urological complications were suspected early and judicious use of 131I hippurate scintiphotographic techniques has proved to be the most helpful method to evaluate patients. If a urological complication did occur prompt recognition and treatment were responsible for a high rate of graft salvage, low incidence of sepsis and absence of patient mortality.

HLA typing and primary cadaver graft survival.

Analysis of 463 consecutive primary cadaver renal transplants showed no influence of HLA match grade on renal allograft survival. Additional categorization according to HLA match grade and degree of presensitization again showed no correlation between match grade and graft survival. Mismatches and matches of specific antigens, cross-reacting groups of antigens, and effect of matching at both locus A and B were also evaluated. There was no significant effect on graft survival except when mismatches against donor A2 and cross-reacting group A2, A28 occurred. A trend toward better graft survival was suggested in recipients matched for A9 and cross-reacting group A9, Aw 23, Aw 24. Although HLA match grade did not influence ultimate graft survival, HLA typing remains important, especially to avoid mismatch against donor A2 antigen. In addition, subsequent detection of new specificities, particularly in other than the A and B loci, may provide significance in the future.

The influence of presensitization on graft survival rate.

Graft survival rate was evaluated in 61 recipients with greater than 50 percent frequency of performed antibodies to selected panel cells. This includes recipients of primary cadaver grafts, secondary cadaver grafts, and living related grafts. Graft survival rate also was evaluated in 199 recipients with pretransplant antibodies reacting with 10 to 50 percent of panel cells and in nonsensitized patients. The results show that good graft survival can be obtained in many hyperimmunized patients, particularly in recipients of primary renal allografts (66 percent cadaver graft survival rate at 2 years). However, sensitization following rejection of an allograft appears to confer a less favorable prognosis. The nature of recipient presensitization and the precise specificity of each reactivity cannot always be explained. This is exemplified in three patients in whom broadly reactive lymphocytotoxic antibodies were not directed against HL-A antigens. Since the number of sensitized patients who await renal transplantation is increasing, there should be no hesitation in proceeding with transplantation, particularly with primary grafts. Emphasis, however, must be placed on frequent prospective recipient serum sampling so that transient high levels of cytotoxins do not escape detection and therefore can be easily selected out for cross-matching against potential donors.