Tissue engineering with dental pulp stem cells: isolation, characterization, and osteogenic differentiation.

INTRODUCTION: Dental pulp stem cells (DPSCs) are adult mesenchymal stem cells that have the ability to differentiate into osteoblasts, a fact that is very interesting in the context of tissue engineering. Our purpose was to isolate and characterize DPSCs and to compare the differentiation potential of 3 different osteogenic media. PATIENTS AND METHODS: Human dental pulp extracted from healthy young adults was placed in flasks with a mesenchymal expansion medium. At passage 4 DPSCs were analyzed for cell-cycle stage, proliferation, viability, and immunophenotype. DPSCs were grown in 3 different osteogenic media for 40 days. Flasks were incubated at 37 °C in 5% CO2, and the medium was changed twice a week. At day 40, the mineralization of the matrix was determined with Alizarin Red S dye. RESULTS: After osteogenic induction, DPSCs developed mineralization nodules (clusters), as revealed by Alizarin Red staining. This staining was stronger in the Osteodiff (Miltenyi) medium when compared to the other osteogenic media. CONCLUSIONS: This study demonstrates the ability of DPSC to differentiate into osteoblasts, especially in the presence of Osteodiff (Miltenyi). DPSCs are therefore a good candidate model for the study of hard-tissue mineralization.

Mesenchymal stem cells derived from dental tissues.

Regeneration of tissues occurs naturally due to the existence of stem cells with the capacity to self-regenerate and differentiate; however, regenerative capacity decreases with age, and in many cases, regeneration is not sufficient to repair the damage produced by degenerative, ischaemic, inflammatory, or tumour-based diseases. In the last decade, advances have been made in the understanding of stem cells, the genes that control the alternative fates of quiescence and differentiation, and the niches that provide specific signals that modulate cell fate decisions. Embryonic stem-cell research is shedding light on the secrets of development. Adult stem cells (AS cells) are available from several sources. Bone marrow and connective tissue have been used in preliminary clinical trials for regenerative therapy. Recently, several types of AS cells have been isolated from teeth, including dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, dental follicle progenitor stem cells and stem cells from apical papilla. Preliminary data suggest that these cells have the capacity to differentiate into osteoblasts, adipocytes, chondrocytes and neural cells. If confirmed, these data would support the use of these cells, which are easily obtained from extracted teeth, in dental therapies, including in regenerative endodontics, providing a new therapeutic modality.

Outcome of children with B cell lymphoma in Venezuela with the LMB-89 protocol.

BACKGROUND: We analyzed the results of the LMB-89 protocol performed in seven centers in Venezuela in 96 children having B-cell non-Hodgkin lymphoma treated from 1995 to 2002. PROCEDURE: Mean age was 7.1 years with 71 (74%) been male. Eighty-two patients (85%) had diffuse small cell lymphoma Burkitt and Burkitt-like, and 14 (15%) had diffuse large B-cell lymphoma. Initial disease sites included the abdomen in 67%, peripheral nodes in 8%, and mediastinal in 4%. Treatment was directed to risk groups as described for LMB-89 protocol. Group A: seven patients (7%), group B: 80 patients (83%), and group C: nine patients (9%). RESULTS: Mean follow-up was 35 +/- 31 months. Complete remission (CR) occurred in 70 patients (73%); four patients (6%) had relapse during the first year and ten patients (10%) had progressive disease. Overall survival (OS) and event free survival (EFS) were 85 and 80% at 1 year, and 82 and 75% at 2 years, respectively. The EFS by therapeutic groups at 3 years was A: 100%; B: 76%, and C: 56%. TOXICITY: neutropenia in 75%, thrombocytopenia in 63%, febrile neutropenia in 39%. Viral infections: hepatitis B in 20%, hepatitis C in 2%, and Herpes zoster in 3%. Tumor lysis syndrome (TLS) occurred in 9% during induction phase with a high mortality of 44% (urate-oxidase was available only at the end of the study). CONCLUSIONS: The high mortality rate during induction phase prohibited a better EFS. Prophylactic use of xantine-oxidase may improve future results. The high incidence of hepatitis B requires a vaccination program.

Treatment of ulcerative colitis with clonidine.

In the present 30-week, double-blind study of 45 ulcerative colitis (UC) patients treated with prednisone, sulfasalazine, clonidine, or placebo, we found that clonidine (an alpha 2 agonist) and prednisone were effective in treating idiopathic UC. Both drugs were more effective than sulfasalazine. Furthermore, clonidine potentiated prednisone and sulfasalazine effects. Clonidine was chosen because its effect on distal colon motility is similar to thioproperazine, an antipsychotic drug that, despite many adverse effects, possesses powerful anti-UC properties. Rating scales were outlined in order to evaluate clinical, endoscopic, histologic, and radiologic changes. Plasma cortisol levels, sedimentation rate, serum glutamic-oxaloacetic transaminase, serum glutamic-pyruvic transaminase, and other biochemical parameters were determined to assess the efficacy of each drug. Distal colon motility changes were also assessed. All our UC patients showed raised cortisol plasma levels and low sigmoidal tone during relapse periods. These parameters were reversed during remission periods. Peripheral and central mechanisms are discussed.

Severe thrombocytopenia following oral cholecystography with iocetamic acid.

We report the first case of severe thrombocytopenia occurring after ingestion of a widely used cholecystographic medium, iocetamic acid. The patient had not been given any treatment before he received the gallbladder contrast medium. Onset of symptoms was acute, and the clinical course was benign with complete recovery after one week. Bone marrow aspiration showed increased numbers of megakaryocytes, suggesting that platelets were rapidly removed from circulation. In vitro tests for antiplatelet antibodies were not performed because iocetamic acid is insoluble in aqueous solutions. Since only a few cases of thrombocytopenia following ingestion of iodine-compounds have been reported, it seems highly unlikely that purpura will be, in the future, a major hazard in cholecystography. However, it would be wise to question patients as to any prior sensitivity to iodine before proceeding with oral cholecystography.

Treatment of ulcerative colitis with thioproperazine.

Thioproperazine, an antipsychotic drug, dramatically improved three ulcerative colitis (UC) patients. We tried this dopaminergic blocking agent in patients with UC because Tp (but not other neuroleptics) suppressed the motility of the distal colon in one patient. All three patients showed impressive improvement by clinical, radiological, endoscopic, histological, and biochemical measures. Although peripheral mechanisms cannot be discarded, we postulate that centrally induced effects offer more satisfactory explanation for the drug's apparent benefit. The fact that Tp, but not other phenothiazine derivatives, penetrate some brain dopaminergic areas could explain Tp's particular effect. We caution that this is a preliminary observation and one that needs confirmation by controlled clinical trials.