A rodent model for testicular involvement in acute lymphoblastic leukaemia

Disease-inducing potential of two leukemic cell lines in a xenografting model

PURPOSE

Cryopreserved ovarian tissue transplant restores ovarian function in young cancer patients after gonadotoxic treatment. However, leukemia is associated with increased risk of malignant cell transmission. We aimed to assess the tumor-inducing potential of two different leukemic cell lines when xenografted to immunodeficient mice.

METHODS

Fifty-four female immunodeficient mice were grafted with either 100, 200, 500, 1000, and 10,000 chronic myeloid leukemia in blast crisis (BV-173) cells or relapsed acute lymphoblastic leukemia (RCH-ACV) cells, embedded inside a fibrin scaffold along with 50,000 human ovarian stromal cells. Two mice per cell line received the fibrin matrix without leukemic cells as negative controls. Clinical signs of disease were monitored for 20 weeks. Grafts, liver tissue, and masses were collected for macroscopic analysis and gene expression of BCR-ABL1 and E2A-PBX fusion transcripts present in BV-173 and RCH-ACV respectively.

RESULTS

BV-173 cells: Mice grafted with 100, 200, or 500 cells showed no sign of disease after and were negative for BCR-ABL1 expression. Three of the 5 animals grafted with 1000 cells and all mice with 10,000 cells developed disease and showed BCR-ABL1-positive expression. RCH-ACV cells: Two out of 4 mice grafted with 100 cells developed disease and were E2A-PBX1-positive. All the animals grafted with higher cell doses showed signs of disease and all but one were E2A-PBX1-positive.

CONCLUSION

The present work proves that the disease-inducing potential of BV-173 and RCH-ACV leukemic cells xenografted to SCID mouse peritoneum differs between cell lines, depending on cell number, type, status, and cytogenetic disease profile when ovarian tissue is harvested.

Testicular involvement of acute lymphoblastic leukemia in children and adolescents: Diagnosis, biology, and management

Acute lymphoblastic leukemia (ALL) in children and adolescents can involve the testes at diagnosis or upon relapse. The testes were long considered pharmacologic sanctuary sites, presumably because of the blood-testis barrier, which prevents the entry of large-molecular-weight compounds into the seminiferous tubule. Patients with testicular involvement were historically treated with testicular irradiation or orchiectomy. With the advent of contemporary intensive chemotherapy, including high-dose methotrexate, vincristine/glucocorticoid pulses, and cyclophosphamide, testicular leukemia present at diagnosis can be eradicated, with the risk of testicular relapse being 2% or lower. However, the management of testicular leukemia is not well described in the recent literature and remains relevant in low- and middle-income countries where testicular relapse is still experienced. Chemotherapy can effectively treat late, isolated testicular B-cell ALL relapses without the need for irradiation or orchiectomy in patients with an early response and thereby preserve testicular function. For refractory or early-relapse testicular leukemia, newer treatment approaches such as chimeric antigen receptor-modified T (CAR-T) cell therapy are under investigation. The control of testicular relapse with CAR-T cells and their penetration of the blood-testis barrier have been reported. The outcome of pediatric ALL has been improved remarkably by controlling the disease in the bone marrow, central nervous system, and testes, and such success should be extended globally. LAY SUMMARY: Acute lymphoblastic leukemia (ALL) in children and adolescents can involve the testes at diagnosis or upon relapse. Modern intensive chemotherapy has largely eradicated testicular relapse in high-income countries. Consequently, most current clinicians are not familiar with how to manage it if it does occur, and testicular relapse continues to be a significant problem in low- and middle-income countries that have not had access to modern intensive chemotherapy. The authors review the historical progress made in eradicating testicular ALL and use the lessons learned to make recommendations for treatment.

Isolated testicular recurrence of B cell acute lymphoblastic leukaemia in an adult: rare case

An 80-year-old man who was previously diagnosed with Philadelphia+ B cell-acute lymphoblastic leukaemia (B-ALL) in remission post-allogeneic matched unrelated donor peripheral blood stem cell transplant. Five years later, he was found to have unilateral testicular relapse of Philadelphia+ B-ALL proven by pathology after radical orchiectomy. Bone marrow aspirate and biopsy did not show evidence of leukaemia. Patient was treated with adjuvant radiation therapy and started on dasatinib 50 mg daily. Given his age and absence of disseminated acutelymphoblastic leukaemia (ALL), no adjuvant chemotherapy was utilised. He is monitored with monthly PCR studies. At 1-year follow-up, no findings suggestive of recurrence of ALL have been identified and the patient is maintained on the dasatinib. Although isolated testicular recurrence is common among paediatric population, it is a rare event among adults as it is considered an immunological sanctuary for cancer cells.

Mechanisms of extramedullary relapse in acute lymphoblastic leukemia: Reconciling biological concepts and clinical issues

Long-term survival rates in childhood acute lymphoblastic leukemia (ALL) are currently above 85% due to huge improvements in treatment. However, 15-20% of children still experience relapses. Relapses can either occur in the bone marrow or at extramedullary sites, such as gonads or the central nervous system (CNS), formerly referred to as ALL-blast sanctuaries. The reason why ALL cells migrate to and stay in these sites is still unclear. In this review, we have attempted to assemble the evidence concerning the microenvironmental factors that could explain why ALL cells reside in such sites. We present criteria that make extramedullary leukemia niches and solid tumor metastatic niches comparable. Indeed, considering extramedullary leukemias as metastases could be a useful approach for proposing more effective treatments. In this context, we conclude with several examples of potential niche-based therapies which could be successfully added to current treatments of ALL.

Is transplantation of a few leukemic cells inside an artificial ovary able to induce leukemia in an experimental model?

PURPOSE

To evaluate the tumor-inducing ability of a few leukemic cells xenotransplanted inside an artificial ovary.

METHODS

Ten and 100 BV-173 leukemic cells were embedded in a fibrin matrix along with 50,000 human ovarian stromal cells, and grafted to the peritoneal bursa of 5 and 5 SCID mice respectively. Four mice grafted with 3x10(6) leukemic cells in fibrin served as positive controls. At 20 weeks post-transplantation, the grafts, liver, spleen, blood and bone marrow were analyzed for the presence of leukemia by anti-CD79α IHC, flow cytometry (FC) and PCR.

RESULTS

All mice grafted with 3x10(6) cells developed peritoneal masses 4 weeks after xenotransplantation, and systemic disease was confirmed by IHC, PCR and FC. Among mice grafted with 10 or 100 leukemic cells, none showed any sign of leukemia after 20 weeks, and IHC, FC and PCR on the different recovered tissues all proved negative.

CONCLUSION

This study investigates the tumor-inducing potential of a few leukemic cells grafted inside an artificial ovary. Transplantation of 100 leukemic cells appears to be insufficient to induce leukemia after 20 weeks. These results in an immunodeficient xenografting model are quite reassuring. However, for clinical application, follicle suspensions must be purged of leukemic cells before grafting, as even the slightest risk should be avoided.

Children with hyperdiploid but not triple trisomy (+4,+10,+17) acute lymphoblastic leukemia have an increased incidence of extramedullary relapse on current therapies: a single institution experience

To evaluate the outcome of children with high hyperdiploid acute lymphoblastic leukemia (hHDALL) treated at the author's institution. One hundred thirty-five consecutive children with B-precursor ALL were diagnosed between 1991 and 2002: 38 (28.1%) hHDALL and 97 (71.9%) non-hHDALL. In the hHDALL group, 11/38 (28.9%) relapsed at a median interval of 2.8 years (range: 0.8-5.0 years) with 9/11 relapses occurring at the end or after the completion of therapy. Three (27.3%) relapses were isolated hematopoietic (BM), while eight (72.7%) were either isolated extramedullary (EM) relapses (n=6; Testis: 4; CNS: 2) or combined hematopoietic and extramedullary relapses (n=2; BM + CNS: 1; BM + Testis: 1). For the non-hHDALL group, 29/97 (29.9%) relapsed. Unlike the hHDALL group, the non-hHDALL group experienced hematopoietic relapses (62%; n=18) more frequently than isolated extramedullary (27.5%; n=8: Testis: 1; CNS: 7) or combined hematopoietic and extramedullary relapses (10.3%; CNS + BM: 3), with 24/29 (82.8%) of the relapses occurring on therapy. Relapses in hHDALL frequently involved EM sites (P=0.053). Presence of triple trisomy of +4,+10,+17 at diagnosis had a protective effect against relapse (P<0.05). Five-year EFS for the hHDALL and non-hHDALL patients was similar, 70.5+/-7.5% and 66.4+/-4.9%, respectively. Five-year OS for the hHDALL patients was significantly higher than for the non-hHDALL patients, 92+/-4.5% vs. 74.1+/-4.5%, P=0.038. Biologically significant differences exist between relapse patterns of hHDALL and non-hHDALL cases related to relapse sites and time periods when relapses occur. hHDALL relapses continue to be chemo-sensitive.

Decontamination of leukemic cells and enrichment of germ cells from testicular samples from rats with Roser’s T-cell leukemia by flow cytometric sorting

Testicular germ cell transplantation is a novel strategy for preservation of fertility in prepubertal cancer patients, but the risk of reseeding tumor cells into cured patients presently limits clinical application of this approach. To date, no systematic evaluation of the limitations of surface marker-based decontamination of testicular samples with acute lymphoblastic leukemia has been performed. Here, surface markers for leukemic (CD4 and major histocompatibility complex class I) and germ cells (epithelia cell adhesion molecule) in testicular samples infiltrated with Roser’s T-cell leukemia were identified. These markers were then used to delete leukemic cells and/or select for germ cells by flow cytometry (FACS). The resulting cell populations were analyzed by FACS, immunocytochemistry, or evaluation of leukemia transmission in syngeneic piebald variegated rats. Simple positive selection of germ cells or deletion of leukemic cells using specific surface markers was unable to effectively decontaminate testicular samples. The poor specificity of spermatogonial surface markers and aggregation of germ and leukemic cells limited the positive selection of germ cells, while immunophenotypic variation among lymphoblastic leukemia cells prevented adequate deletion of leukemic cells. Enzymatic treatment to disperse the testicular cells and feature of the intratesticular environment contributed to this immunophenotypic variation. Only germ cell selection in combination with leukemic cell deletion prevented leukemia transmission in association with intratesticular injection of the sorted cells. However, with such combined sorting, only 0.23% of the original testicular cells were recovered. With presently available techniques, flow cytometric purification of germ cells from a leukemic donor is not sufficiently effective or safe for clinical use.

Induced leukemia and antineoplastic agent carmustine cause permanent changes in craniofacial growth of immature rats

OBJECTIVES

The purpose of the present study was to investigate the possible effects of untreated terminal leukemia on craniofacial growth (Study I), and also the effects of the antineoplastic agent carmustine on craniofacial growth in both leukemic and healthy rats (Study II).

MATERIAL

A total of 367 inbred Piebald variegated rats was used.

METHOD

Transmission of leukemic cells was carried out intraperitoneally at 30 days of age, and without treatment (Study I), the rats reached the terminal phase within 17 +/- 1 days. Rats with induced leukemia was cured with 10 mg/kg carmustine (BCNU) given on days 6 and 13 following cell transmission (Study II), the rats remaining in remission until they were killed at 100 days of age. Final weight was recorded and 12 craniofacial dimensions and tibial length were measured with a digital sliding caliper.

RESULTS

The results showed that the effect of untreated terminal rat leukemia (Study I) on craniofacial growth differed between the genders. Male rats showed clearly reduced dimensions of facial structures and also retarded general body growth, whereas females showed differences mainly in general body growth. The effect of cured leukemia (Study II) as such was minor, while BCNU had a strong and permanent reducing effect on both craniofacial and general body growth in both genders.

CONCLUSION

We suggest that the results in Study I came both from a direct effect of leukemia and an indirect effect of untreated terminal leukemia through malnutrition. The alkylating agent BCNU seemed to be the main cause of permanent craniofacial and general growth retardation in Study II.

Acute lymphoblastic leukaemia in rats induces pathomorphological changes in germ cells

Concern about the reproductive potential of long-term survivors of acute lymphoblastic leukaemia (ALL) prompted an investigation into the impact of the disease on spermatogenic cells. Using rats as a model, histological, immunocytochemical and electron microscopic analysis was applied to investigate changes in the seminiferous epithelium. In rats transplanted with leukaemic cells at early puberty, degenerate primary spermatocytes and spermatids were prevalent within stage VIII tubules. Electron microscopically, step 8 spermatids showed acrosomal abnormalities and nuclear contour distortion. In the distorted step 9 spermatids, the microtubules of the manchette were abnormally oriented or deficient. Antitubulin antibody staining was reduced in elongating spermatids in the group transplanted with leukaemic cells at early puberty but was not observed in the older leukaemic group. Step 13 spermatids showed extracted chromatin and degenerate step 19 spermatids were occasionally found. Similar but less severe changes were seen in the group of rats transplanted with leukaemic cells at late puberty. We conclude that germinal cell damage induced by ALL is dependent on the developmental maturity of the seminiferous epithelium. The present findings are of particular importance when interpreting the impact of anticancer chemotherapeutics on germinal cells in patients with ALL.

Effects of testicular cytokines on proliferation of rat T-leukaemic lymphoblasts in vitro

A rat acute lymphoblastic leukaemia (ALL) model was used to study the mechanisms involved in the tendency to testicular relapse of ALL in boys. Previous studies have indicated that the infiltration and growth of leukaemic lymphoblasts in the testis are influenced by the same endocrine and paracrine control systems that regulate normal testicular function. In the present study the effects of aqueous extracts of scrotal, abdominal and estrogen-treated postpubertal rat testes on rat-leukaemic lymphoblast proliferation were evaluated. The effects of recombinant cytokines analogous to those observed in the testis on leukaemic cell DNA-synthesis were also evaluated since changes in the levels of these factors have been observed in association with cryptorchidism and low levels of gonadotropins. Transforming growth factor-beta 1 (TGF-beta1), significantly inhibited the proliferation of leukaemic rat lymphoblasts after 24 h of culture, whereas TGF-beta 2, interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6 or combinations of them were inactive. Extracts of estrogen-treated testes and abdominal testes of unilaterally cryptorchid animals inhibited leukaemic T-cell proliferation significantly more than extracts of normal testes. The inhibitory activity in abdominal testes could be neutralized by anti-TGF-beta 1 antibodies. These results suggest that testicular TGF-beta 1 may influence growth of leukaemic lymphoblasts in the testis but also that other as yet unknown, testicular factors are involved in the regulation of leukaemic cell function in the testis.

Spread of malignant lymphoid cells into rat central nervous system with intact and disrupted blood-brain barrier

The pathways of spread of malignant lymphoid cells into the central nervous system (CNS) were studied using a T lymphoblastic leukaemia/lymphoma model of inbred PVG rats. The effects of intraperitoneal, intracarotid, intravenous, intrathecal and intracerebral routes of transplantation were analysed, and the significance of the blood-brain barrier (BBB) in preventing neoplastic cell invasion was studied by disrupting the BBB with focal cold injury. Extraneurally transplanted cells appeared first in the dura and subarachnoid space. From the latter they spread further into the perivascular space of penetrating cortical vessels. Parenchymal tumour cell foci were only seen in terminally ill rats, usually associated with damage to the vessel wall. Intrathecal transplantation did not accelerate the progression of the disease. Intracerebrally transplanted cells readily produced parenchymal infiltrates with diffuse invasion into the white matter, perivascular spreading into the cortex, and contralateral extension along the corpus callosum. Parenchymal invasion did not occur immediately after disruption of the BBB, but in the chronic phase neoplastic cells infiltrated the injured area. In conclusion, the model closely resembles human CNS leukaemia. Malignant cells appeared to enter the CNS through the deficient BBB of the subarachnoid vessels, whereas the BBB of the intracerebral vessels and perivascular glia limitans were very resistant to leukaemic cell invasion. This underlines the difference between the subarachnoid and perivascular v. intraparenchymal compartments. Preceding BBB damage may predispose to brain metastases. The parenchymal dissemination of malignant cells was similar to that in primary CNS lymphoma and it followed the same spreading pathways as the extracellular fluid.