Bone marrow transplantation for genetic disorders

Regenerative endodontics: a review of current status and a call for action

Millions of teeth are saved each year by root canal therapy. Although current treatment modalities offer high levels of success for many conditions, an ideal form of therapy might consist of regenerative approaches in which diseased or necrotic pulp tissues are removed and replaced with healthy pulp tissue to revitalize teeth. Researchers are working toward this objective. Regenerative endodontics is the creation and delivery of tissues to replace diseased, missing, and traumatized pulp. This review provides an overview of regenerative endodontics and its goals, and describes possible techniques that will allow regenerative endodontics to become a reality. These potential approaches include root-canal revascularization, postnatal (adult) stem cell therapy, pulp implant, scaffold implant, three-dimensional cell printing, injectable scaffolds, and gene therapy. These regenerative endodontic techniques will possibly involve some combination of disinfection or debridement of infected root canal systems with apical enlargement to permit revascularization and use of adult stem cells, scaffolds, and growth factors. Although the challenges of introducing endodontic tissue engineering therapies are substantial, the potential benefits to patients and the profession are equally ground breaking. Patient demand is staggering both in scope and cost, because tissue engineering therapy offers the possibility of restoring natural function instead of surgical placement of an artificial prosthesis. By providing an overview of the methodological issues required to develop potential regenerative endodontic therapies, we hope to present a call for action to develop these therapies for clinical use.

Parental consent for bone marrow transplantation in the case of genetic disorders

PURPOSE

To describe the responses of mothers and fathers who were offered bone marrow transplantation (BMT) for their children with genetic disorders.

DESIGN

Qualitative.

SETTING

Private hospital rooms/offices.

PARTICIPANTS

Six mothers and 4 fathers of children with genetic disorders.

RESULTS

The basic social-psychological problem confronting the parents was the conflicting alternatives of life versus death for their children. It was certain that these children would die from their genetic disorders but without having to endure the pain and suffering of a BMT. The BMT would be difficult, possibly resulting in death, but with a chance of survival.

CONCLUSIONS

Parents believed that BMT was the only chance of survival for their children, leaving them no choice except to pursue the BMT treatment.

Relationships between ablation of distinct haematopoietic cell subsets and the development of donor bone marrow engraftment following recipient pretreatment with different alkylating drugs

A number of different alkylating chemotherapeutic agents--busulphan, dimethylbusulphan (DMB), isopropylmethane sulphonate (IMS), melphalan, cyclophosphamide (CY) and bischloroethylnitrosourea (BCNU)--were investigated for their cytotoxic effects on different haemopoietic cell populations in host mice and for their ability to induce short- and long-term engraftment of transplanted bone marrow. At 24 h after drug treatment the femoral content of transient and permanent repopulating stem cell subsets was assessed, respectively, from the frequency of early- (day 5-15) and late- (day 25-35) developing cobblestone area-forming cells (CAFCs), growing in vitro in long-term bone marrow cultures (LTBMCs). At this time a fixed complement of 10(7) congenically marked donor bone marrow cells (B6-Gpi-1a-->B6-Gpi-1b) was infused in the drug-treated mice and erythroid engraftment was followed over 36 weeks. Diverse effects on early- and late-developing CAFC frequencies were found for the different drugs; these were generally related to the pattern of donor bone marrow engraftment in treated recipients. Melphalan was more toxic to early-developing than to late-developing CAFC subsets, and the transplant only offered an early wave of blood chimerism followed by return of host cells. CY and BCNU had minimal to moderate effects on CAFC content and engraftment with no apparent preference for any particular haemopoietic cell subset. IMS also had a relatively low toxic effect on host marrow CAFC frequencies but appeared exceptional in its ability to allow for more donor-type engraftment. The dimethane sulphonate compounds busulphan and DMB were especially potent at depleting late CAFC subsets and ensured high and lasting levels of donor bone marrow engraftment. These studies support the value of CAFC measurements for predicting the fate and growth of transplanted bone marrow cells in recipients pretreated with a variety of cytotoxic agents.

Immunosuppressive therapy in bone marrow transplantation

Immunosuppressive and immunomodulatory techniques have a central role in bone marrow transplantation (BMT). A wide range of agents with different mechanisms of action, including steroids, cyclosporin, cytotoxic agents, irradiation and monoclonal antibodies are used to achieve the following treatment aims: (1) Suppression of the recipient's immunity to permit donor marrow engraftment and prevent graft rejection; (2) Prevention of graft versus host disease (GvHD); (3) Treatment of established acute or chronic GvHD.