Nimotuzumab and radiotherapy for treatment of newly diagnosed diffuse intrinsic pontine glioma (DIPG): a phase III clinical study.

BACKGROUND: Diffuse intrinsic pontine glioma (DIPG) is a devastating cancer of childhood and adolescence. METHODS: The study included patients between 3 and 20 years with clinically and radiologically confirmed DIPG. Primary endpoint was 6-month progression-free survival (PFS) following administration of nimotuzumab in combination with external beam radiotherapy (RT). Nimotuzumab was administered intravenously at 150 mg/m2 weekly for 12 weeks. Radiotherapy at total dose of 54 Gy was delivered between week 3 and week 9. Response was evaluated based on clinical features and MRI findings according to RECIST criteria at week 12. Thereafter, patients continued to receive nimotuzumab every alternate week until disease progression/unmanageable toxicity. Adverse events (AE) were evaluated according to Common Terminology Criteria for Adverse Events (CTC-AE) Version 3.0 (CTC-AE3). RESULTS: All 42 patients received at least one dose of nimotuzumab in outpatient settings. Two patients had partial response (4.8%), 27 had stable disease (64.3%), 10 had progressive disease (23.8%) and 3 patients (7.1%) could not be evaluated. The objective response rate (ORR) was 4.8%. Median PFS was 5.8 months and median overall survival (OS) was 9.4 months. Most common drug-related AEs were alopecia (14.3%), vomiting, headache and radiation skin injury (7.1% each). Therapy-related serious adverse events (SAEs) were intra-tumoral bleeding and acute respiratory failure, which were difficult to distinguish from effects of tumor progression. CONCLUSIONS: Concomitant treatment with RT and nimotuzumab was feasible in an outpatient setting. The PFS and OS were comparable to results achieved with RT and intensive chemotherapy in hospitalized setting.

Bloodstream infection in paediatric cancer centres--leukaemia and relapsed malignancies are independent risk factors.

UNLABELLED: In a prospective multicentre study of bloodstream infection (BSI) from November 01, 2007 to July 31, 2010, seven paediatric cancer centres (PCC) from Germany and one from Switzerland included 770 paediatric cancer patients (58% males; median age 8.3 years, interquartile range (IQR) 3.8-14.8 years) comprising 153,193 individual days of surveillance (in- and outpatient days during intensive treatment). Broviac catheters were used in 63% of all patients and Ports in 20%. One hundred forty-two patients (18%; 95% CI 16 to 21%) experienced at least one BSI (179 BSIs in total; bacteraemia 70%, bacterial sepsis 27%, candidaemia 2%). In 57%, the BSI occurred in inpatients, in 79% after conventional chemotherapy. Only 56 % of the patients showed neutropenia at BSI onset. Eventually, patients with acute lymphoblastic leukaemia (ALL) or acute myeloblastic leukaemia (AML), relapsed malignancy and patients with a Broviac faced an increased risk of BSI in the multivariate analysis. Relapsed malignancy (16%) was an independent risk factor for all BSI and for Gram-positive BSI. CONCLUSION: This study confirms relapsed malignancy as an independent risk factor for BSIs in paediatric cancer patients. On a unit level, data on BSIs in this high-risk population derived from prospective surveillance are not only mandatory to decide on empiric antimicrobial treatment but also beneficial in planning and evaluating preventive bundles. WHAT IS KNOWN: • Paediatric cancer patients face an increased risk of nosocomial bloodstream infections (BSIs). • In most cases, these BSIs are associated with the use of a long-term central venous catheter (Broviac, Port), severe and prolonged immunosuppression (e.g. neutropenia) and other chemotherapy-induced alterations of host defence mechanisms (e.g. mucositis). What is New: • This study is the first multicentre study confirming relapsed malignancy as an independent risk factor for BSIs in paediatric cancer patients. • It describes the epidemiology of nosocomial BSI in paediatric cancer patients mainly outside the stem cell transplantation setting during conventional intensive therapy and argues for prospective surveillance programmes to target and evaluate preventive bundle interventions.

Treatment of recurrent primitive neuroectodermal tumors (PNET) in children and adolescents with high-dose chemotherapy (HDC) and stem cell support: results of the HITREZ 97 multicentre trial.

Early studies with high-dose chemotherapy for treatment of relapsed cerebral PNET had shown modest efficacy but considerable toxicity. The HIT97 national trial tested a nonrandomized but stratified relapse protocol using either intensive chemotherapy, potentially high dose, or oral chemotherapy. 72 patients (59 disseminated) whose primary treatment had been surgery (97 %), radiotherapy (88 %), and/or chemotherapy (95 %) were enrolled in the intensive chemotherapy arm at diagnosis of relapse or resistance. As a window for this study they received two courses of a 96-hour infusion with carboplatin and etoposide. A response (complete or partial remission) was documented by MRI. Responders received two more cycles of this therapy and stem cell collection, before they received HDC (carboplatin, etoposide, thiotepa) and stem cell support. All possibilities of local therapy were to be explored and applied. After two courses of chemotherapy there was a 52 % response rate (41/72 patients). The median PFS and OS for all 72 patients were 11.6 and 21.1 months. Patients with medulloblastoma had a longer PFS and OS (12.6 and 22.6 months) than those with other PNETs (3.1 and 12.3 months). Favourable prognostic features were no new signs of clinical impairment and localised disease at relapse diagnosis. For the 27 patients who received HDC the median PFS and OS were 8.4 and 20.2 months, respectively. HDC did not benefit patients with resistant cerebral PNET and was associated with profound haematological and mucosal toxicity (90-100 % grade III, IV), infections (50 % grade III and IV) and severe ototoxicity (50 % grade III, 12.5 % grade IV). Treatment related mortality was 8 %. There was low long-term survival and only 2/72 patients are in continuous remission. Adding HDC in patients who responded to the initial courses of chemotherapy did not improve survival. Patients with relapsed cerebral PNET who respond to conventional chemotherapy do not profit from further augmentation to HDC.

Skin tolerance is supported by the spleen.

The repeated application of antigens results in the induction of tolerance. Lymph nodes are responsible for this reaction by producing suppressor cells. Using an in vivo transplantation model, we showed recently that stromal cells from different lymph nodes induce different cell populations for suppression, which all produce a tolerogenic phenotype. In this study, we were interested in the role of the spleen in these tolerance reactions. Therefore, tolerance was induced via feeding or injecting ovalbumin several times in control and splenectomized mice. The delayed-type hypersensitivity (DTH) was measured as well as the cell subset composition of the spleen. The spleen of peripherally tolerized mice showed higher proliferation activity and a specific antibody production compared with orally tolerized mice, where regulatory T cells were predominantly found. Tolerance induction after removal of the spleen resulted in a reduced DTH response in antigen fed animals, whereas skin tolerance induction failed. In conclusion, the results illustrate that lymph nodes from different areas employ their individual pathways for similar immune reactions, and the spleen is part of this reaction initiated at the peripheral site.

Lymph node dissection--understanding the immunological function of lymph nodes.

Lymph nodes (LN) are one of the important sites in the body where immune responses to pathogenic antigens are initiated. This immunological function induced by cells within the LN is an extensive area of research. To clarify the general function of LN, to identify cell populations within the lymphatic system and to describe the regeneration of the lymph vessels, the experimental surgical technique of LN dissection has been established in various animal models. In this review different research areas in which LN dissection is used as an experimental tool will be highlighted. These include regeneration studies, immunological analysis and studies with clinical questions. LN were dissected in order to analyse the different cell subsets of the incoming lymph in detail. Furthermore, LN were identified as the place where the induction of an antigen-specific response occurs and, more significantly, where this immune response is regulated. During bacterial infection LN, as a filter of the lymph system, play a life-saving role. In addition, LN are essential for the induction of tolerance against harmless antigens, because tolerance could not be induced in LN-resected animals. Thus, the technique of LN dissection is an excellent and simple method to identify the important role of LN in immune responses, tolerance and infection.

Bloodstream infections in paediatric cancer patients. Prospective comparative study in 2 university hospitals.

BACKGROUND: Preventive approaches (including those related to care of long term central venous catheters, CVADs) and the incidence of bloodstream infections (BSI) in 2 German university affiliated paediatric oncology units. PATIENTS AND METHODS: Non-interventional prospective observational study using the Oncoped surveillance module. Center A included 85 patients in 31 months and Center B 84 patients in 21 months. The populations did not differ in terms of age, gender, malignancy and disease status (first illness vs. relapse). Center A used ports (46 %) and 2 different Broviac catheters (54 %), in Center B nearly all patients with a CVAD had Broviacs (96 %). 30 BSI (24 patients) were diagnosed in Centre A and 28 BSI (22 patients) in Center B. Patients with relapsed malignancy experienced more BSI (51.4 % vs. 20.9 %; p = 0.001). Incidence rates were significantly lower in Center A (3.47 vs. 7.93 BSI/1000 CVAD days; p = 0.037). Poisson regression analysis revealed a significant lower incidence density (BSI/100 inpatient days) for all BSI in Center A (RR 0.47 CI95 0.27-0.81, p = 0.006). Overall, 52 % of all pathogens detected in blood cultures in Center A were Gram-positive (57 % in Center B) and 48 % Gram-negative (43 in Center B). One ALL patient without a CVAD died due to overwhelming sepsis caused by an ESBL-producing E. cloacae isolate. CONCLUSION: Paediatric cancer treatment centers differ substantially in regard to management of CVADs and in other preventive strategies. The most important use of local surveillance data is longitudinal internal assessment in close cooperation with microbiology and hospital hygiene experts.

Aortobifemoral embolism in an 18-year old patient following cisplatin and 5-fluorouracil chemotherapy for nasopharyngeal carcinoma.

After cisplatin / 5-fluorouracil chemotherapy for nasopharyngeal carcinoma, an 18-year female patient developed aortobifemoral embolism. Besides chemotherapy, additional risk factors for arterial thromboembolic events were smoking, contraceptive medication and adjuvant antiemetic treatment with dexamethasone. Thrombophilia screening was negative. Thromboembolic complications during or after cisplatin have been reported in a frequency of 17.6 % in lung cancer patients, and in 8.4 % of patients with germ cell tumors. The incidence of arterial thromboembolic events was 9.3 % and 1.7 %, respectively. The pathogenesis of cisplatin induced thromboembolism is thought to be caused by endothelial damage leading to endothelial cell dysfunction, increased von Willebrand factor plasma levels, and hypomagnesaemia.

Compassionate use of bevacizumab (Avastin) in children and young adults with refractory or recurrent solid tumors.

BACKGROUND: The aim of this study was to evaluate feasibility and toxicity of bevacizumab (Avastin), a monoclonal antibody directed against the vascular endothelial growth factor in children and young adults. PATIENTS AND METHODS: Fifteen patients (male: n = 8; female: n = 7; median age, 14.6 years) received bevacizumab for recurrent or progressive solid tumors (carcinoma: n = 3; neuroblastoma: n = 2; astrocytoma grade III: n = 2; rhabdomyosarcoma: n = 2; nephroblastoma: n = 2; benign vascular tumors: n = 2; synovial sarcoma: n = 1; and malignant hemangiopericytoma: n = 1) on a compassionate basis. Bevacizumab was administered at 5-10 mg/kg body weight intravenously every 2-3 weeks. Most patients received chemotherapy in addition to bevacizumab. Duration of bevacizumab therapy ranged from 1.5 to 23 months. RESULTS: Bevacizumab-related side-effects were mild and included hypertonia (n = 2), proteinuria/hematuria (n = 2), epistaxis (n = 2), local erythema (n = 1), and defective wound healing and ascites (n = 1). Radiographic objective responses (partial responses) were observed in two patients with astrocytoma grade III and in one patient each with neuroblastoma and pleomorphic rhabdomyosarcoma, respectively. CONCLUSIONS: Bevacizumab seems to have a good acute safety profile and some antitumor activity in heavily pretreated children and young adults with recurrent solid tumors. Prospective clinical trials are urgently needed to further evaluate the safety and efficacy of bevacizumab in pediatric patients.

Sexual precocity associated with an abdominal tumor in an African boy.

We report a 3 year-old boy in Tanzania with an abdominal mass and isosexual precocity due to an hCG-secreting hepatoblastoma. Due to the limited availability of local diagnostic testing, surgery and chemotherapy were completed before immunohistochemical and endocrine results were available.

[Pediatric renal cell carcinoma. A rare differential diagnosis of Wilms' tumor]. / Das Nierenzellkarzinom beim Kind. Eine seltene Differenzialdiagnose zum Wilms-Tumor.

Renal cell carcinoma (RCC) is a very rare pediatric disease and should be treated as an entity of its own because of differences in symptoms, therapy, and prognosis from the adult form of the disease. Our objective is to discuss the difficulties in clinical diagnosis, prognosis, and therapy of this very rare disease in children and to provide a review of the current literature.

Marked elevation in homocysteine and homocysteine sulfinic acid in the cerebrospinal fluid of lymphoma patients receiving intensive treatment with methotrexate.

OBJECTIVE: Interference of methotrexate (MTX) with the metabolism of homocysteine may contribute to MTX neurotoxicity. In this pilot study we measured the concentration of homocysteine and related metabolites in the cerebrospinal fluid (CSF) of patients with primary central nervous system lymphoma undergoing intensive treatment with MTX. MATERIAL AND METHODS: CSF samples from lymphoma patients (n = 4) were drawn at the end of high-dose MTX infusions (3-5 g/m2/24 h, HDMTX) and one day after intraventricular injections of MTX (3 mg, ICVMTX) or cytarabine (30 mg) and analyzed for homocysteine, cysteine, sulfur-containing excitatory amino acids (cysteine sulfinic acid, cysteic acid, homocysteine sulfinic acid and homocysteic acid), S-adenosylmethionine, 5-methyltetrahydrofolate and MTX. The concentration of homocysteine, cysteine and sulfur-containing excitatory amino acids were also measured in the CSF of a reference population not exposed to MTX. The Wilcoxon signed rank-test and the Friedman test were used to compare concentrations of homocysteine and its metabolites at various time-points during chemotherapy. Comparison of patient and control samples were performed using the Mann-Whitney U-test. Allelic variants of homocysteine metabolism previously shown to influence MTX neurotoxicity (MTHFR c.677C>T, MS c.2756A>G and Tc2 c.776C>G) were also analyzed. RESULTS: After application of HD- and ICVMTX, the CSF homocysteine concentrations in the lymphoma patients were markedly elevated and significantly higher than those in the control group (p < 0.05, Mann-Whitney U-test), whereas 5-methyltetrahydrofolate was depleted. A rapid elevation of homocysteine sulfinic acid, a sulfur-containg amino acid which was not detected in the CSF of the control group, was observed. One patient developed confluent white matter brain changes visible using MRI. This patient had the lowest concentration of S-adenosylmethionine in the CSF and carried two risk alleles for MTX neurotoxicity. CONCLUSIONS: In this pilot study, MTX administered either intravenously or intraventricularly, induced marked biochemical alterations in the CSF. Whether these changes can be used to predict MTX-induced neurotoxicity at an early stage in treatment needs to be elucidated in larger clinical trials.

Effect of medical honey on wounds colonised or infected with MRSA.

Full healing was achieved in seven consecutive patients whose wounds were either infected or colonised with methicillin-resistant Staphylococcus aureus. Antiseptics and antibiotics had previously failed to irradicate the clinical signs of infection.

[Coating with plasma-deposited functionalized diamond-like carbon to decrease encrustations on urological implants]. / Plasmadeponierte funktionalisierte Kohlenstoffschichten zur Minderung von Inkrustationen auf urologischen Implantaten.

The double-J stents used today for palliative artificial urinary diversion very often show extreme formation of encrustations, even a short time after implantation. Despite increased scientific material development, the complication rate has not really been strongly influenced. Grant-aided by the German Federal Ministry of Education and Research, we chose a new interdisciplinary and translational approach by coating standard stent materials with plasma-deposited amorphous diamond-like carbon. These stents show clearly reduced rates of encrustation in vitro. Ongoing clinical trials demonstrate a further enhancement of this effect in vivo. The underlying mechanisms are being investigated by extending the established in vitro model, thereby pushing research in this field to a new level.

Diagnosis and treatment of catheter-related infections in paediatric oncology: an update.

Otherwise unexplained clinical signs of infection in patients with long-term tunnelled or totally implanted central venous access devices (CVADs) are suspected to be CVAD-associated. Diagnostic methods include catheter swabs, blood cultures and cultures of the catheter tip or port reservoir. In the case of a suspected CVAD-related bloodstream infection in paediatric oncology patients, in-situ treatment without prompt removal of the device can be attempted. Removal of the CVAD should be considered if bacteraemia persists or relapses > or = 72 h after the initiation of (in-vitro effective) antibacterial therapy administered through the line. Timely removal of the device is also recommended if the patient suffers from a complicated infection, or if Staphylococcus aureus, Pseudomonas aeruginosa, multiresistant Acinetobacter baumannii or Candida spp. are isolated from blood cultures. Duration of therapy depends on the immunological recovery of the patient, the pathogen isolated and the presence of related complications, such as thrombosis, pneumonia, endocarditis and osteomyelitis. Antibiotic lock techniques in addition to systemic treatment are beneficial for Gram-positive infections. Although prospectively controlled studies are lacking, the concomitant use of urokinase locks and taurolidine secondary prophylaxis seem to favour catheter salvage.

Changes in the translational activity of polyadenylated messenger RNA of HL60 promyelocytic leukemia cells associated with myeloid or macrophage differentiation.

In order to characterize the events which commit the HL60 human promyelocytic leukemia cell line to differentiate into macrophages or mature myeloid cells, we have analyzed the in vitro [35S]methionine-labeled translational products obtained from polyadenylated messenger RNA of the HL60 cells before and after exposure to: (a) dimethylformamide (DMF), an inducer of myeloid differentiation; (b) 12-O-tetradecanylphorbol-13-acetate (TPA), an inducer of macrophage differentiation; or (c) a combination of the two inducers. Exposure of the HL60 cells to either TPA or DMF results in decreases in the relative abundancy of translational products with molecular weights of 20,000, 17,000, and 15,000. Exposure of the HL60 cells so as to generate macrophage differentiation results in elevations of translational products with molecular weights of 60,000, 47,000, 42,000, 32,000, 27,000, 14,000, and 12,300, while DMF-induced myeloid differentiation is associated with increases in the abundancy of translational products with molecular weights of 60,000, 42,000, 35,000, 32,000, 27,000, 13,000 and 12,300. The addition of the macrophage inducer TPA to HL60 cells previously exposed to the myeloid inducer DMF results in changes in the relative abundance of several translational products, yielding a pattern which differs quantitatively from that obtained from cells treated with DMF or TPA alone. These changes in the relative abundancies of the HL60 translational products suggest that the steady state levels of several different populations of mRNA or the ability of these mRNAs to be translated are being modified during the induction of myeloid or macrophage differentiation in the HL60 promyelocytic leukemia cell line.

Active transport of methotrexate from cerebrospinal fluid in humans.

The cerebrospinal fluid (CSF) efflux kinetics of methotrexate (MTX) were studied in three patients with indwelling Ommaya reservoirs. A small dose of MTX was injected intraventricularly several hr after the start of a high-dose continuous i.v. infusion of MTX. In all patients, the CSF antifolate concentration returned to the preinjection level before the end of the i.v. infusion. This result indicated that the efflux of MTX from CSF in humans is independent of plasma drug concentrations. Efflux kinetics were further characterized in one patient. Serially obtained CSF samples after intraventricular injections demonstrated a biphasic disappearance curve with alpha- and beta-phase half-disappearance times of 1.7 and 6.6 hr, respectively. Prolongation of the beta-phase half-time was associated with oral acetazolamide medication and with increased intracranial pressure, indicating that inhibition of CSF production slows MTX clearance. CSF MTX concentration, however, declined more rapidly than that of simultaneously administered diethylenetriaminepentaacetic acid, an extracellular marker substance excreted by bulk flow, indicating that bulk flow excretion alone is insufficient to account for MTX efflux from human CSF. Evidence that there is an active transport component was provided by probenecid pretreatment which also prolonged the CSF MTX half-life. These findings suggest that both passive and active mechanisms govern MTX efflux from the CSF in humans and that they can be inhibited by acetazolamide and probenecid, respectively.

Methotrexate pharmacokinetics and prognosis in osteosarcoma.

PURPOSE: The influence of methotrexate (MTX) pharmacokinetic parameters on the efficacy of high-dose MTX (HDMTX) in osteosarcoma was analyzed. PATIENTS AND METHODS: MTX serum peak values from 198 patients in 1,703 treatment courses and more detailed pharmacokinetic data from 185 patients in 1,045 treatment courses from the Cooperative Osteosarcoma Study Group (COSS) studies COSS-80, COSS-82, and COSS-86 were investigated. RESULTS: A mean threshold peak level of > or = 1,000 mumol/L for the repeated MTX courses of individual patients was found to correlate significantly to prognosis in study COSS-80 (18% v 64% actuarial 10-year disease-free survival [DFS], P = .0001). Six courses of HDMTX per patient who achieved peak values > or = 1,000 mumol/L were found to be sufficient for a full effect to be seen in DFS in COSS-80. The MTX peak level was found to correlate closely to the area under the curve (AUC). However, AUC was a less powerful determinator of prognosis than the mean threshold MTX peak value. In patients who received cisplatin (DDP) as one of the additional drugs to MTX, the peak values and AUC were significantly increased (1,396 v 1,276 mumol/L, P = .011; 6,684 v 5,820 h.mumol/L, P < or = .002) and only a few patients (6%) did not achieve mean threshold MTX peak values. In addition, following restriction of hydration fluid after the MTX infusion from 4.5 to 3.0 L/m2 per 24 hours, the early MTX half-life (t1/2) and the AUC, but not the MTX peak value, were significantly increased (3.4 v 3.05 hours, and 6,760 v 5,998 h.mumol/L, respectively, P < or = .002). CONCLUSION: MTX pharmacokinetics significantly influence the efficacy of MTX in osteosarcoma. Individual adaptation of the MTX dose to ensure a threshold peak serum level > or = 1,000 mumol/L does not seem necessary at a fixed dose of 12 g MTX/m2, restriction of hydration fluid to 3 L/m2 per 24 hours, and concomitant use of DDP within the drug regimen.

Stromal cells as trend-setters for cells migrating into the lymph node.

Lymph node stromal cells are known to be immunorelevant during inflammation and tolerance. Differences between peripheral lymph nodes and mesenteric lymph nodes are important for an efficient and effective immune defense. Stromal cells were considered to be perfectly adapted to their draining area and not changeable concerning their expression pattern. Here we show that stromal cells can change their profile after isolation and transplantation into a different draining area. Subsequently, these newly organized lymph nodes are able to induce not only a region-specific but also an antigen-specific immune response. Thus, stromal cells are trend-setters for immune cells in producing a microenvironment that allows an optimized immune defense.

Efficiency and toxicity of ifosfamide, cisplatin and doxorubicin in the treatment of childhood hepatoblastoma. Study Committee of the Cooperative Paediatric Liver Tumour Study HB89 of the German Society for Paediatric Oncology and Haematology.

The Cooperative German Paediatric Liver Tumour Study HB89 was conceived to evaluate the efficiency and toxicity of ifosfamide, cisplatin and doxorubicin (IPA) in children with resectable and non-resectable hepatoblastoma (HB) and to determine late sequelae including tubular nephropathy of tumour treatment. The study also assessed the results of a surgical strategy, which adapts the procedure at the initial operation to the tumour's extension in the liver. The relationship of the tumours' histological differentiation to response to chemotherapy was also examined. Patients with a HB restricted to one liver lobe underwent primary resection. Larger tumours were initially treated with IPA chemotherapy and resected at second-look surgery. All patients received IPA adjuvantly after tumour resection. The IPA regimen consisted of ifosfamide 3.5 g/m2 (over 72 h days 1-3), cisplatin 100 mg/m2 (over 5 days 4-8) and doxorubicin 60 mg/m2 (over 48 h, days 9-10). Median follow-up of survivors was 64 months (range 28-82). Long-term disease-free survival (DFS) was for stage I: 21/21; stage II: 3/6; stage III: 28/38; and stage IV: 2/7 (overall 75%). Severe surgical complications occurred in 15% (4/27) of primary and 21% (8/38) of secondary resections with no lethality. 44/45 stage III/IV HB displayed PR after two IPA courses. Drug resistance developed in 8/12 tumours after four or five chemotherapy courses. Acute toxicity was observed in 34/242 (14%) IPA courses. Late sequelae were found in 7/54 (13%) of survivors, and subclinical renal tubulopathy occurred in 7/41 investigated patients (17%). Despite a more favourable prognosis in pure fetal and predominantly fetal histology, statistical analysis revealed no relationship between tumour differentiation and response to chemotherapy. In conclusion, IPA chemotherapy in combination with delayed surgery was highly effective in the treatment of HB.

Regeneration of implanted splenic tissue in the rat: re-innervation is host age-dependent and necessary for tissue development.

The loss of spleen may lead to fatal bacterial infections. To prevent this, splenic autotransplantation has been performed in humans and experimental animals. However, there is still controversy about the protective function of this procedure. Since innervation plays an important role in splenic function, we investigated whether splenic regenerates are re-innervated, and whether this depends on the donor and host age. Splenic tissue (30 mg) was implanted into the greater omentum of either young (2 days) or old (12 months) rats, from either young or old syngeneic animals. After 3 months of regeneration, the weight of the regenerates was determined, PGP+ nerve fibers were revealed by immunohistology, and subdivided into nerve fibers of sympathetic (TH+, NPY+) or sensory (SP+, CGRP+) origin. In addition, proliferating (Ki-67 proliferation antigen+) and apoptotic cells (TUNEL technique+) were likewise investigated. No innervation of splenic regenerates was observed after implantation into old hosts, correlating with poorly developed splenic compartments. In contrast, almost normal re-innervation occurred in young hosts after implantation of both young and old splenic tissue. These regenerates showed well-developed splenic compartments and a normal number and tissue distribution of proliferating and apoptotic cells. However, after the implantation of young tissue, the final size of splenic regenerates was three times larger (140 +/- 30 vs. 40 +/- 10 mg). Thus, re-innervation of splenic implants is necessary for their subsequent development. It is determined by host age, whereas the final size of the splenic regenerates is regulated by donor age-dependent factors. This model is useful for studying both the process leading to initial innervation and the consequences of this innervation.