A model for preservation of thymocyte-depleted thymus

DiGeorge syndrome is a disorder caused by a microdeletion on the long arm of chromosome 22. Approximately 1% of patients diagnosed with DiGeorge syndrome may have an absence of a functional thymus, which characterizes the complete form of the syndrome. These patients require urgent treatment to reconstitute T cell immunity. Thymus transplantation is a promising investigational procedure for reconstitution of thymic function in infants with congenital athymia. Here, we demonstrate a possible optimization of the preparation of thymus slices for transplantation through prior depletion of thymocytes and leukocyte cell lineages followed by cryopreservation with cryoprotective media (5% dextran FP 40, 5% Me2SO, and 5% FBS) while preserving tissue architecture. Thymus fragments were stored in liquid nitrogen at -196°C for 30 days or one year. The tissue architecture of the fragments was preserved, including the distinction between medullary thymic epithelial cells (TECs), cortical TECs, and Hassall bodies. Moreover, depleted thymus fragments cryopreserved for one year were recolonized by intrathymic injections of 3×106 thymocytes per mL, demonstrating the capability of these fragments to support T cell development. Thus, this technique opens up the possibility of freezing and storing large volumes of thymus tissue for immediate transplantation into patients with DiGeorge syndrome or atypical (Omenn-like) phenotype.

Heart transplantation in pediatric population and in adults with congenital heart disease: long-term follow-up, critical clinical analysis, and perspective for the future

BACKGROUND

Heart transplantation is a treatment option for children as well as for adults with congenital heart disease.

OBJECTIVE

To report the experience of a tertiary center with heart transplant program in pediatric population and in adults with congenital heart disease.

PATIENTS AND METHODS

The study consisted of the evaluation of pediatric as well as adult patients undergoing heart transplantation for congenital heart disease. We evaluated the following indication and complications such as renal dialysis, graft vascular disease, tumors and survival.

RESULTS

From October 1992 to November 2013, 134 patients had transplantation, and there were 139 transplantations and 5 retransplantations. The immunosuppression regimen is based on calcineurin inhibitors and cytostatic drugs. The type of heart disease indicated for transplantation was cardiomyopathies in 70% and congenital heart disease in 30%. Of these 134 patients, 85 patients were alive. Actuarial survival is 77.4%, 69.6%, 59.3% at 1, 5, and 10 years after transplantation. Three patients underwent renal transplantation, 1 patient is in renal dialysis, and 8.2% of patients had post-transplant lymphoproliferative disease. Two patients had retransplantation for graft vascular disease; 1 of them required a simultaneous kidney transplant and died 30 days after the procedure and 1 patient is clinically well 2 years after retransplantation.

CONCLUSION

Heart transplantation in children and in adults with congenital heart disease is a promising therapeutic option and enables long-term survival for these patients.

Heart transplantation in neonates and children. Intermediate-term results

OBJECTIVE

To assess intermediate-term outcome in children who have undergone orthotopic heart transplantation.

METHODS

We carried out a longitudinal and prospective study between October '92 and June '99 comprising 20 patients with ages ranging from 12 days to 7 years (mean of 2.8 years). We employed a double immunosuppression protocol with cyclosporine and azathioprine and induction therapy with polyclonal antithymocyte serum. Survival and complications resulting from the immunosuppression protocol were analyzed.

RESULTS

The double immunosuppression protocol and the induction therapy with polyclonal antithymocyte serum resulted in an actuarial survival curve of 90% and 78.2% at 1 and 6 years, respectively, with a mean follow-up period of 3.6 years. One patient died due to acute rejection 40 days after transplantation; another patient died 2 years after transplantation due to lymphoproliferative disorder; a third patient died because of primary failure of the graft; and a fourth patient died due to bronchopneumonia. The major complications were as follows: acute rejection, infection, nephrotoxicity, and systemic hypertension. The means of rejection and infection episodes per patient were 2.9 and 3.4, respectively. After one year of transplantation, a slight reduction in the creatinine clearance and systemic hypertension were observed in 7 (38.9%) patients.

CONCLUSION

Heart transplantation made life possible for those patients with complex congenital heart diseases and cardiomyopathies in refractory congestive heart failure constituting a therapeutical option for this group of patients in the terminal phase.

[Neonate and infant heart transplantation]

PURPOSE

Heart transplantation has offered children with complex congenital heart diseases and severe cardiomyopathies a chance for survival. The present article was written to show the three year experience of this procedure at the Instituto do Coração-HCFMUSP.

METHODS

The methodology used was based on heart transplant indication criteria, inclusion criteria for donors, postoperative management, immunosuppression and prophylaxis as well as treatment of potential complications.

RESULTS

From November 1992 to November 1995, 11 children, aged 12 days old to six years (mean 2.5 years) underwent transplantation. Sixty percent of recipients were male; weight ranged from 3.5 to 17.8 kg (mean 10.3 kg). The mean age of donors was 4.4 years (a range of three weeks to ten years), 80% male, weight ranging from 3.8 to 20 kg (median 14.3 kg). The survival rate was 91% and the remaining 10 children are doing well. The most important complications were systemic hypertension, acute rejection and infection. The number of rejections and infections per patient were 3.5 and 4.7 episodes, respectively. The follow-up was between one month to three years (average 16 months).

CONCLUSION

In this experience, heart transplantation has given an additional opportunity for children with complex congenital heart diseases and cardiomyopathies, with a survival rate of 91% in three years.