PubMed Health⌕ Search

Biomedical subjects

J Case

Publications and source records attributed to J Case.

At least 19 recordsLinked to original sources
PubMed1997

Cytokine-mediated expansion does not deplete cord blood cells with stem cell characteristics.

Cord blood (CB) has been successfully used to regenerate the hematopoietic system after myeloablative therapy. We investigated whether cytokine mediated expansion depletes CB of cells with stem cell characteristics. CB mononuclear cells (MNC) were enriched for quiescent (primitive) stem cells by incubation with 25 micrograms/ml 5-Fluorouracil (5-FU) and control CB MNC were incubated with media alone. Cells were then incubated for 7 days with Interleukin-1 (IL1)+IL3+Stem Cell Factor (SCF) and progenitor content, cell cycle status, nucleated cell count, immunophenotype and resistance to 25 micrograms/ml 5-FU (primitive stem cells) were evaluated before and after cytokine exposure. Incubation with IL1+IL3+SCF caused an increase (fold expansion) in committed (28.6 +/- 8.1), immature (5.8 +/- 1.8), and primitive progenitors (4.1 +/- 0.8) among control CB MNC compared to a decrease in committed progenitors (0 +/- 0) but an increase in both immature (8.4 +/- 4.8) and primitive progenitors (7 +/- 2.9) among 5-FU resistant CB MNC. An increase in the proportion of CD34+ cells occurred in both fractions. Expanded control CB MNC showed a significant increase in numbers of 5-FU resistant committed (p = 0.024), immature (p = 0.014) and primitive progenitors (p = 0.01) as compared with fresh CB MNC. Re-exposure of 5-FU resistant expanded CB MNC to 5-FU shows growth of some immature and primitive progenitors. Cytokine-mediated expansion of untreated and quiescent CB cells is possible and cytokine-mediated expansion does not deplete CB cells with stem cell characteristics.

Antigens, CD34↗
PubMed1997

Cytokine mediated expansion of human umbilical cord blood CD34+ cells: comparison of the use of partially purified and pure CD34+ target cells.

To determine the optimal cell population for cytokine mediated expansion, we compared the use of Magnetic Cell Sorting (MACS) system enriched CD34+ human umbilical cord blood (HUCB) cells with that of MACS enriched, flow purified CD34+ HUCB cells. Both MACS enriched CD34+ cells and MACS enriched, flow purified CD34+ cells (mean starting purity of CD34+ SC 51.27 +/- 7.6% and 96.36 +/- 1.34% respectively n = 6) were incubated for seven days with Interleukin-1 (IL-1) + IL-3 + Stem Cell Factor (SCF) and showed a fold increase in the number of nucleated cells (10.02 +/- 2.6 and 18.23 +/- 4.73 respectively) and a reduction in the percentage of CD34+ cells (5.55 +/- 1.23% and 12.21 +/- 3.29% respectively). An increase in the absolute numbers of CD34+ cells (4.8 x 10(4) +/- 2.3 x 10(4)) was observed with MACS enriched CD34+ cells as compared to no change (1.3 x 10(5) +/- 8.8 x 10(4) with MACS enriched, flow purified CD34+ cells. An increase in IL-3 + GM-CSF + SCF responsive colony forming unit (CFU) (1.7 x 10(4) +/- 9.4 x 10(3) and 1.6 x 10(5) +/- 7.7 x 10(4) respectively) was also observed as compared with input values (1.5 x 10(4) +/- 1 x 10(4) and 2.3 x 10(4) +/- 8.9 x 10(3) respectively). We conclude that MACS enriched, flow sorted CD34+ HUCB cells have greater cytokine mediated expansion potential as measured by progenitor expansion, than MACS enriched CD34+ HUCB cells.

Antigens, CD34↗
PubMed1996

Conditions affecting the isolation of human umbilical cord blood CD34+ cells.

The magnetic cell sorting (MACS) system was used to isolate CD34+ human umbilical cord blood (HUCB) stem cells (SC). Variables that might affect the detection of CD34+ cells, purity, enrichment, and yield of CD34+ cells, and the co-expression by CD34+ cells of CD38 and HLA-DR and their clonogenic capabilities were investigated. These variables were (a) separation technique [Ficoll, Percoll mononuclear cell (MNC) preparation] and (b) storage of HUCB [fresh, stored overnight (O/N) at 4 degrees C or frozen]. There was no difference between MNC prepared for MACS CD34+ SC isolation by Ficoll or Percoll separation. The use of fresh, O/N, or frozen HUCB did not affect the isolation of CD34+ SC.

Antigens, CD34↗
PubMed1988

Replicate tests for the detection and correction of errors in anti-human globulin (AHG) tests: optimum conditions and quality control.

Replicate blind AHG tests with weak IgG anti-D sensitised red cells revealed that 32% of workers caused 5 per cent or more false negative errors by using excessive agitation in reading techniques. The common quality control procedure of adding strongly sensitised cells to all negative AHG tests cannot reveal this type of error. Furthermore, strongly sensitised control cells may create an illusion of safety because AHG giving a false negative test with weak antibody in a serum sample may still show a reassuringly strong positive in the control test. "In-house" assessment of all staff and automatic cell-washers by blind replicate tests is recommended as an effective way of improving AHG test performance, thus reducing many of the errors involving false negative AHG tests seen year after year in External Proficiency Trials.

Antibodies↗