Peripheral blood progenitor cell mobilization in three groups of subjects: a comparison of leukapheresis yield and timing

In this review, we analyse the peripheral blood progenitor cell mobilization yield of three categories of subjects including group 1, healthy allogeneic donors given growth factors; group 2, patients with haematological malignancies mobilized with chemotherapy followed by growth factors; and group 3, patients with solid tumours mobilized with growth factors alone. A wide variation amongst subjects of the same category was observed. Group 1 and group 2 patients mobilized to a similar degree with a mean CD34(+) yield/kg of 3.44 x 10(6) and 3.39 x 10(6) respectively, for a standardized 2. 5 times blood volumes processed. This is superior to group 3 patients mobilized with growth factors alone who yielded only 0.99 x 10(6)/kg. A good correlation between peripheral blood CD34(+) count and leukapheresis yield was observed for all three groups. For healthy donors, prescheduled leukapheresis on day 5 after growth factors commencement predicts good yield, obviating the need for CD34 monitoring. On the contrary, most cancer patients mobilized with growth factors alone as in group 3 have inadequate single collection. They invariably require cumulative yield of several collections for adequate dose and hence predicting timing with peripheral blood CD34(+) count is not useful. In group 2 patients mobilized with chemotherapy followed by growth factors, we find that a peripheral blood CD34(+) count of 11/microL predicts collection of more than 1 x 10(6) CD34(+) cell/kg/2.5 blood volumes, thus helping to maximize yield and resources. J. Clin. Apheresis, 15:217-223, 2000.

Variability in CD34+ cell counts in umbilical cord blood: implications for cord blood transplants

OBJECTIVE

To determine if total nucleated cell counts alone are sufficient for predicting the efficacy of cord blood units for transplant from neonatal umbilical cord blood samples.

METHODS

Umbilical cord blood samples were collected from 200 mothers at delivery and the cord blood units processed. The total nucleated cells and CD34+ cells were enumerated and compared for each sample.

RESULTS

Despite an apparent linear correlation between total nucleated cell counts and CD34+ cell counts, each group of total nucleated cell counts demonstrated a high degree of variation in CD34+ cell counts and could be as low as 0.1% of total nucleated cell counts.

CONCLUSIONS

Large variations in CD34+ cell counts per total nucleated cell count are present for cord blood units from neonatal umbilical cord samples. Hence a CD34+ cell count for each cord blood unit would improve selection of samples for transplant.

Molecular and phenotypic spectrum of de novo Philadelphia positive acute leukemia

The Philadelphia chromosome is present in a heterogeneous group of leukemias. It is most commonly associated with chronic myelogenous leukemia (CML) and B-lineage acute lymphoblastic leukemia (ALL) being found in more than 95% and 15-25% of cases respectively. We undertook a study to determine the morphologic, phenotypic and molecular diversity of Philadelphia positive de novo acute leukemia patients seen at our institution over the past 3 1/2 years. Twenty-one patients with de novo acute leukemia were found to have the Philadelphia chromosome by cytogenetic studies. They consisted of 3 patients with acute myelogenous leukemia (AML), 1 biphenotypic leukemia and 17 ALL patients. Of the patients with ALL, 16 were of B-lineage while 1 had a T-cell phenotype. Ten patients expressed the p210 BCR-ABL transcript alone and 10 expressed only the p190 BCR-ABL transcript. One patient had co-expression of p190 and p210 b3a2 BCR-ABL transcripts. Thus the Philadelphia chromosome can be found in a diverse cohort of morphologic and immunologic subtypes of de novo acute leukemia reflecting the heterogeneity of lineage involvement in this disease.

A study of the xenogeneic response in an isolated liver perfusion circuit--preliminary observations

An isolated liver perfusion circuit was developed to study the xenogeneic reaction of human blood to porcine liver, and investigate the feasibility of using such a system for liver dialysis in fulminant hepatic failure. Three experimental groups were studied: a control group where pooled porcine blood was perfused through pig liver (n = 12), a xenogeneic group where banked human blood was perfused through porcine liver (n = 23), and a modified xenogeneic group where decomplemented human blood was perfused through porcine liver (n = 4). The following parameters of liver function were assessed: liver function tests, serum electrolytes, bile and ascites production. In addition, liver histology was assessed at the start and completion of each perfusion experiment. Control experiments established that the use of low perfusion pressures (mean inlet pressure of 29.5 +/- 7.4 mmHg), and low haematocrit of 20.5 +/- 8.9% (n = 14), enabled five hour perfusions to be consistently achieved with maintenance of normal acid base and electrolyte balance. Bile production over 5 hours was 18.8 +/- 8.0 ml in controls (n = 5) and 17.0 +/- 6.7 ml in the xenogeneic (human-pig) circuit (n = 11) (NS). Ascites production was 235.8 +/- 157.3 ml/hr in controls (n = 5) and 205 +/- 142.0 ml/hr in the xenogeneic circuit (n = 7) (NS).(ABSTRACT TRUNCATED AT 250 WORDS)

An in vitro assessment of human fetal pancreatic islets of Langerhans in culture

The human fetal pancreas is a potential source of islets for transplantation into insulin-dependent diabetic patients. In this study, 35 human fetal pancreas obtained from prostaglandin-induced abortions (12-26 weeks gestation), were placed in culture to determine their capacity to secrete insulin over 30 days. Culture media were sampled twice weekly for insulin and histology was performed serially. Of the 35 pancreases cultured, six were lost due to bacterial contamination, five discarded due to undetectable levels of insulin in culture, nine are still under study, whilst 15 pancreases have been cultured for one month, and insulin studies completed. Three patterns of insulin release were observed: (a) progressive decline (n = 6), indicating non-viable tissue at the onset; (b) delayed decline, indicating significant tissue damage before organ culture (n = 5); and (c) insulin production in vitro over 30 days (n = 4), with viable islets detected histologically. Factors such as gestational age and cold ischaemia time did not correlate with the pattern of insulin secretion observed. This was probably due to a more important variable, not easily assessed, of the period of intrauterine (warm) ischemia. These data suggest: (1) that a small number of fetal pancreases procured from prostaglandin-induced abortuses do yield islets which remain viable in culture over 30 days, and (2) the functional status of islets can be monitored in vivo by measuring insulin secretion, thereby providing a means of identifying tissue suitable for transplantation.

Fetal pig pancreas--a preliminary assessment of tissue for transplantation

Porcine fetal pancreases (PFP) obtained from 4 pregnant sows were pooled, minced into 1 mm3 fragments and studied in organ culture for up to 30 days to determine tissue viability and insulin production in vitro. After 7-9 days in culture, some of these explants were transplanted into euglycemic, N:NIH-nu(s) nude recipient mice, and studied histologically over 69 days following grafting. Using RPMI 1640 supplemented with 5% fetal calf serum as the culture medium in 90% air/10% CO2, it was found that explants were viable with insulin production detected in vitro, which was maximal at day 7 (197 +/- 18.9 mU/L, n = 11), and gradually declined thereafter. By 22 days, insulin levels were less than 60.1 +/- 28.5 mU/L (n = 6). Histology of the explants showed viable tissue with evidence of mitoses present in insulin-positive cells at day 16 in vitro. Beyond this time, tissue viability diminished. Explants transplanted into euglycemic nude mice did not undergo rejection during the observation period of 69 days. Grafts remained viable with evidence of an increase in mitotic activity in the endocrine tissue on immunoperoxidase staining. These preliminary investigations confirm that pancreatic explants from porcine fetuses can be maintained in culture for up to 16 days. Such explants, when transplanted under the kidney capsule of euglycemic, nude mice, did not undergo necrosis, but remained viable, with evidence of mitoses in the islet tissue.