Effective transplantation of photoreceptor precursor cells selected via cell surface antigen expression.

Retinal degenerative diseases are a major cause of untreatable blindness. Stem cell therapy to replace lost photoreceptors represents a feasible future treatment. We previously demonstrated that postmitotic photoreceptor precursors expressing an NrlGFP transgene integrate into the diseased retina and restore some light sensitivity. As genetic modification of precursor cells derived from stem cell cultures is not desirable for therapy, we have tested cell selection strategies using fluorochrome-conjugated antibodies recognizing cell surface antigens to sort photoreceptor precursors. Microarray analysis of postnatal NrlGFP-expressing precursors identified four candidate genes encoding cell surface antigens (Nt5e, Prom1, Podxl, and Cd24a). To test the feasibility of using donor cells isolated using cell surface markers for retinal therapy, cells selected from developing retinae by fluorescence-activated cell sorting based on Cd24a expression (using CD24 antibody) and/or Nt5e expression (using CD73 antibody) were transplanted into the wild-type or Crb1(rd8/rd8) or Prph2(rd2/rd2) mouse eye. The CD73/CD24-sorted cells migrated into the outer nuclear layer, acquired the morphology of mature photoreceptors and expressed outer segment markers. They showed an 18-fold higher integration efficiency than that of unsorted cells and 2.3-fold higher than cells sorted based on a single genetic marker, NrlGFP, expression. These proof-of-principle studies show that transplantation competent photoreceptor precursor cells can be efficiently isolated from a heterogeneous mix of cells using cell surface antigens without loss of viability for the purpose of retinal stem cell therapy. Refinement of the selection of donorphotoreceptor precursor cells can increase the number of integrated photoreceptor cells,which is a prerequisite for the restoration of sight.

A phase I-II study of dacarbazine in combination with outpatient interleukin-2 in metastatic malignant melanoma.

Because of encouraging response rates published with recombinant interleukin-2 (rIL-2) alone in metastatic malignant melanoma (MMM), dacarbazine (DTIC) and rIL-2 were sequentially combined to evaluate efficacy, toxicity, pharmacokinetics, and immunologic interaction. Thirty-two patients aged 18 to 67 years have received 127 courses of treatment. The dose of DTIC was 1.0 g/m2 as a 24-hour infusion every 28 days on day 1. Recombinant interleukin-2 (2.0, 3.0, 4.0, or 5.0 x 10(6) Cetus units/m2) was administered as a 30-minute infusion on days 15 through 19 and 22 through 26 of each 28-day cycle. Seven of 32 patients (22%) who received therapy had a remission, one complete and six partial. The complete response was in a lung mass. Partial responses were seen in lymph nodes, liver, and lung. The median duration of response was 4.7 months. One patient is in persistent partial remission of the liver for greater than 2 years. One patient had residual mediastinal disease resected after partial response and remains without evidence of disease for 18+ months. This regimen was generally well tolerated, did not create overlapping toxicity, and produced encouraging responses in visceral sites. This provides a framework for future combinations of chemotherapy with rIL-2 alone or in combination with other biologic response modifiers in an outpatient setting.

Age-associated changes in parathyroid hormone in black males.

To examine changes in calcium metabolism related to aging in blacks and caucasians, we measured serum mid-molecule parathyroid hormone (PTH), total and ionised calcium in 83 black and 47 caucasian healthy males aged 31-77 yrs. Age and race were without effect on total or ionised calcium. PTH levels increased significantly (P less than 0.03) with age in black but not caucasian subjects. These results demonstrate an aging-associated increase in circulating PTH in blacks and are consistent with other data from our laboratory which suggest that PTH may be involved in the development of salt-sensitive hypertension in blacks.

Racial differences in mineral intake in ambulatory normotensives and hypertensives.

This study was designed to determine dietary mineral intake of black and white normotensives and hypertensives and to identify specific food categories which contribute to observed differences. Sixty-six subjects completed 4-day dietary intake records. Nutrient intake was estimated and patterns of food intake were determined. There were racial differences in dietary mineral intake with both white normotensives and hypertensives ingesting more potassium than their black counterparts and white normotensives consuming more calcium and magnesium than white hypertensives and both groups of blacks. White normotensives also used more high sodium chloride foods than did other groups. It appears that decreased intake of potassium and calcium in blacks may account, in part, for the increased tendency to salt sensitivity and hypertension in this population.

Reductions in total and extracellular water associated with calcium-induced natriuresis and the antihypertensive effect of calcium in blacks.

Previous data from this laboratory suggest that Ca-induced reductions in blood pressure may result in part from Ca-induced natriuresis and a possible reduction in intravascular volume. Consequently, the present study was conducted to directly determine the relative effects of dietary Ca and Na on total body water (TBW) and extracellular water (ECW) as measured by tetrapolar bioelectrical impedance and to determine the potential relationship of these changes to diet-induced changes in blood pressure. Eleven hypertensive black adults were maintained for 14 days on each of four diets that contained 356 mg Ca or 1,000 mg Ca, each at 1,000 or 4,000 mg Na in a repeated measures design. Increasing dietary Na at the low Ca intake caused significant increases in supine systolic and diastolic pressure, reduced plasma renin activity (PRA), significantly increased TBW, and caused a significant reduction in total body reactance indicating an increase in ECW. Adding supplementary Ca to the low Na diet was without significant effect on blood pressure, PRA, TBW, or electrical reactance. In contrast, adding Ca to the low Ca-high Na diet caused a significant natriuretic effect that was accompanied by significant increases in PRA and electrical reactance and significant reductions in blood pressure and TBW, to baseline (low Ca-low Na levels). Thus, these data indicate that the antihypertensive effect of calcium in salt-sensitive blacks may be attributable, in part, to Ca-induced natriuresis and an associated volume contraction.