Efficient ex vivo expansion of NOD/SCID-repopulating cells with lympho-myeloid potential in hematopoietic grafts of children with solid tumors.

INTRODUCTION: The ex vivo expansion of hematopoietic grafts could be an important therapeutic tool for accelerating hematopoietic recovery after administration of high-dose chemotherapy regimens. The fate of the long-term repopulating cells during the ex vivo manipulation of grafts is a critical issue and will ultimately define the clinical applicability of this technology to hematopoietic transplantation. MATERIALS AND METHODS: To study the effects of a clinically applicable ex vivo expansion protocol in the proliferative potential of the most primitive human hematopoietic cells, both LTC-IC and NOD/SCID-RC assays were used to determine LTC-IC and NOD/SCID-RC contents of hematopoietic grafts, both before and after expansion (SCF, IL-3, PEG-MGDF Flt3-L and 5% AB serum), in four children with non-hematological malignancies. RESULTS: The mean percentage of CD34+ cells after expansion was 16%. The numbers of nucleated cells increased 20-fold with a mean three-fold increase in the numbers of CD34+ cells during the expansion period. The CFC content of the samples showed a mean 11-fold increase (range: 5-17) after ex vivo expansion. The primitive hematopoietic stem cell content of the expanded cell fraction evaluated by LTC-IC assays was found to be increased in two patients out of three, with maintenance of the LTC-IC frequency in the third patient. The NOD/SCID-RC potential, evaluated in five experiments from four patients using 109 mice injected 5-6 weeks earlier with human hematopoietic cells, increased from a mean percentage of 36% (range: 7-75%) before expansion, to a mean percentage of 70% (range: 37-100%) after expansion (P < 0.00001). The frequency of NOD/SCID-RC calculated with pooled data from all patients was 1/80,000 at day 0 and 1/40,000 after seven days of culture. The full phenotypic analysis of human hematopoietic cells obtained in NOD/SCID mice injected with expanded cells showed the presence of significant numbers of CD34+, CD19+ and CD15+ cells, suggesting the persistent lympho-myeloid potential of the expanded hematopoietic cells. CONCLUSION: Our results suggest that efficient expansion of NOD/SCID-RC with lympho-myeloid potential can be achieved not only in cord blood or normal marrow as previously reported, but also in hematopoietic grafts obtained from children exposed to high-dose chemotherapy.

Rhabdomyosarcoma of the larynx in children: a series of five patients treated in the Institut Gustave Roussy (Villejuif, France).

Rhabdomyosarcoma of the larynx is a malignant disease rarely seen in children. We present five cases (3 males, 2 females) observed among 126 patients with rhabdomyosarcoma of the head and neck (excluding the orbit) treated in the Institut Gustave-Roussy between 1955 and 1981. The patients were aged between 5 1/2 years and 13 1/2 years at the time of diagnosis. The presenting symptoms were dysphonia and/or dyspnea; tracheotomy was required in two cases. All five patients received chemotherapy consisting of vincristine, cyclophosphamide, actinomycin D + procarbazine or doxorubicin. Four patients also received radiotherapy (45 Gy during 5 weeks). Laryngectomy was not performed. Treatment sequelae included regional hypoplasia, huskiness, and subclinical thyroid insufficiency; two patients developed a benign thyroid adenoma. One patient presented a bilateral carotid stenosis subsequent to radiotherapy performed on "wide fields" portal designed to provided prophylactic treatment on uninvolved lymph nodes. All the patients are alive and relapse-free with a follow-up of between 13 and 17 years. This small series of RMS of the larynx shows that patients can be cured without laryngectomy, although long-term sequelae associated with radiotherapy are observed.