Receptors could boost transplant effectiveness

The identification of what scientists are calling a "homing" receptor could boost the effectiveness of transplants by guiding stem cells to bone marrow.

"In the future, this approach might improve the success of human bone marrow transplantation," says lead researcher Tsvee Lapidot, MD, of the Weizmann Institute of Science in Rehovot, Israel. The results of the study appear in the Feb. 5, 1999, issue of the journal Science.

During bone marrow transplantation, diseased marrow is destroyed and replaced with donated marrow containing stem cells. Stem cells have the ability to develop into healthy blood cells and are injected into the bloodstream of transplant patients with hopes of replenishing the marrow cavities of the patient’s bones. Ethical issues remain largely unresolved regarding the collection and storage of stem cells.

Researchers sought to see if a specific receptor on the surface of stem cells acts as a homing device and naturally attracts the cell to marrow. The researchers found that, with human stem cells injected into mice, stem cells with CXCR4 receptors migrated successfully to marrow.

The CXCR4 receptor, in turn, appears to be attracted to SDF-1, which is a compound released by bone marrow cells. "We discovered that human stem cells are sort of like sailing boats," Lapidot explains. "A sailing boat will pick up the wind only if its sail is put up on the mast; similarly, stem cells will migrate to the bone marrow only if they display a specific receptor on their surface that allows them to pick up the signals from marrow cells."

Lapidot estimates that 10% of stem cells are naturally equipped with the CXCR4 receptor, but that all stem cells have the potential to grow the receptor. He points out his own research team’s success at growing receptors. Researchers cultured stem cells in the laboratory with natural growth factors and boosted the CXCR4-bearing cells to more than 90%.

Elderly rarely die at home, study finds

Half of elderly patients receiving long-term home care die in the hospital, according to a report in the January issue of the Journal of the American Geriatrics Society.

In fact, only one out of five elderly patients die at home, according to researchers. Researchers point out that they were "unable to obtain the patient and family preferences for site of death," in order to determine if dying at home was a planned event for the study participants.

Characteristics of those more likely to die at home included:
• being female;
• being severely dependent functionally;
• experiencing mental deterioration;
• having illnesses, such as cancer, chronic lung disease, or coronary artery disease.

Researchers studied 620 patients over age 65 who died within a year of being admitted to a community long-term care program during 1989 and 1990. Overall, 49% died in the hospital, 21% at home, 20% in a nursing home, and 7% in an inpatient hospice.

Be truthful to kids about HIV

Children and teens infected with the HIV virus should be told by their physician and parents, according to a recently published policy statement.

The Chicago-based American Academy of Pediatrics recommended to its 55,000 members in January to be frank toward HIV-infected children. The policy statement was published in the January 1999 issue of the association’s journal Pediatrics.

The policy recommends that physicians work with parents to convince them that their child should know the truth about their HIV status. The policy does not, however, suggest that physicians tell the child against the parents’ objections unless the patient is a sexually active teen.

The organization previously has not taken a position on the issue but decided to because the problem is becoming more serious. Children are becoming infected with HIV, and they are living longer, the policy points out.

While only preliminary research has been conducted on the effects of telling youngsters about their condition, an initial study shows that disclosing the information may be beneficial. Youngsters who are told have higher self-esteem and parents who are candid with children are less likely to be depressed.