Stem Cell Therapy in Dentistry: An Overview.

Cells with a unique capacity for self-renewal and potency are called stem cells. With appropriate biochemical signals stem, cells can be transformed into desirable cells. Regeneration of oral and maxillofacial structures is earned out by using stem cell therapy, and this has gained momentum in recent days. Future tissues like tissue engineered bone grafts, engineered joints and cranial sutures can be developed with stem cell therapy. We have described the properties, types and advantages of dental stem cells. Emphasis is been given to the possibilities of stem cell therapy in the oral and maxillofacial region including regeneration of tooth and craniofacial defects.

Cytotherapy for Osteonecrosis of Hip.

Osteonecrosis of hip is a pathological condition that leads to collapse of the femoral head, & the need for total hip replacement (THR). Research has shown that at the cellular level there is decrease in osteoblastic activity & the local mesenchymal stem cells (MSC) population that leads to osteonecrosis of femoral head (ONFH). Cellular therapy could thus be used to improve the local cellular environment. Th is can be achieved by implanting bone marrow, containing osteogenic precursors into the necrotic lesion of the femoral head.

Biology and clinical utilization of mesenchymal progenitor cells

Within the complex cellular arrangement found in the bone marrow stroma there exists a subset of nonhematopoietic cells referred to as mesenchymal progenitor cells (MPC). These cells can be expanded ex vivo and induced, either in vitro or in vivo, to terminally differentiate into at least seven types of cells: osteocytes, chondrocytes, adipocytes, tenocytes, myotubes, astrocytes and hematopoietic-supporting stroma. This broad multipotentiality, the feasibility to obtain MPC from bone marrow, cord and peripheral blood and their transplantability support the impact that the use of MPC will have in clinical settings. However, a number of fundamental questions about the cellular and molecular biology of MPC still need to be resolved before these cells can be used for safe and effective cell and gene therapies intended to replace, repair or enhance the physiological function of the mesenchymal and/or hematopoietic systems

Tissue restoration, tissue engineering and regenerative medicine

Recently, thanks to the rapid progress of new technologies in cell modulation, extracellular matrix fabrication and synthetic polymers mimicking bodily structures, the self-regeneration of bodily defects by host tissue has been considered by many researchers. The conventional science of art in biomaterials has been concerned with restoring damaged tissue using non-biological materials such as metals, ceramics and synthetic polymers. To overcome the limitations of using such non-viable materials, several attempts to construct artificial organs mimicking natural tissue by combining modulated cells with extracellular matrix-hybridized synthetic polymers have produced many worthy results with biologically functioning artificial tissues. The process involved in manufacturing biomaterials mimicking living tissue is generally called tissue engineering. However recently, the extension of knowledge about cell biology and embryology has naturally moved the focus from tissue restoration to tissue regeneration. Especially, embryonic and mesenchymal stem cells are attractive resources due to their potential for the differentiation of various tissue cells in response to signal transduction mediated by cytokines. Although no one knows yet what is the exact factor responsible for a stem cell's ability to differentiate between specific cells to generate specific tissue, what has been agreed is that delivering stem cells into the body provides a strong potential for the regeneration of tissue. In this review, the historical issues and future possibilities involved in medical tissue restoration and tissue regeneration are discussed.

Transplantation of neural stem cells: cellular & gene therapy for hypoxic-ischemic brain injury

We have tracked the response of host and transplanted neural progenitors or stem cells to hypoxic-ischemic (HI) brain injury, and explored the therapeutic potential of neural stem cells (NSCs) injected into mice brains subjected to focal HI injury. Such cells may integrace appropriately into the degenerating central nervous system (CNS), and showed robust engraftment and foreign gene expression within the region of HI inury. They appeared to have migrated preferentially to the site of ischemia, experienced limited proliferation, and differentiated into neural cells lost to injury, trying to repopulate the damaged brain area. The transplantation of exogenous NSCs may, in fact, augment a natural self-repair process in which the damaged CNS "attempts" to mobilize its own pool of stem cells. Providing additional NSCs and trophic factors may optimize this response. Therefore, NSCs may provide a novel approach to reconstituting brains damaged by HI brain injury. Preliminary data in animal models of stroke lends support to these hypotheses.

Estudo randomizado comparativo do transplante alogênico de medula óssea e células progenitora periférica, mobilizada por G-CSF, näo manipulada em neoplasias hematológicas

Resumo: Este é um estudo randomizado, desenvolvido com base alogênica de medula óssea (MO) e aqueles de células progenitoras periféricas (CPP), os quais säo utilizados no tratamento de doenças hematológicas malignas. Para tal, deu-se ênfase à pega, à doença do enxerto contra o hospedeiro (DECH) aguda e crônica, bem como às sobrevidas dos pacientes. De 02/1995 até 10/1997, 40 pacientes receberam um transplante HLA adêntico, originado da MO (grupo A) ou CPP (grupo B). O total de pacientes avaliáveis no final do estudo foi de 19 (gurpo A) e 18 (grupo B), respectivamente. A mediana de idade foi de 35 anos (17-56) no grupo A e 29,5 (9-51) no grupo B (P=0,17). O regime de condicionamento utilizado foi Bu (16)/Cy(120) em 16 pacientes no grupo A e 17 no grupo B; Bu(16)/Cy(120)/VP-16(40) em 3 pacientes no grupo A e Cy (120)/irradiaçäo corporal total (ICT)(13,2Gy) em 1 paciente no grupo B. A profilaxia da DECH utilizada foi ciclosporina (CSP)/Metotrexato em 16 pacientes no grupo A e em pacientes no grupo B; e 3 pacientes receberam CSP/prednisona no grupo A, As CPP foram mobilizadas com G-CSF, 10ug/kg/dia, durante 5 dias e colhidas no quinto dia, em uma única sessäo de aférese, na maioria dos pacientes. O conteúdo mediano de células CD34+x10.6/kg/receptor foi de 5,26(1,19-15,55) no grupo A e 4,71(1,26-71,61) no grupo (P=0,40). A mediana de dias para se atingir o número absoluto de neutrófilos (NAN)>0,5 x 10/foi de 18(13-30) no grupo A e 16(11-25)no grupo B(P=0,15).

Coleta de células progenitoras periféricas por método de hemaféreses / A Guideline of peripheral blood progenitor cells collect by hemapheresis

Os autores apresentam uma proposta de protocolo para coleta de células progenitoras periféricas destinadas aos transplantes autólogos e alogênicos de Medula Ossea obtidas por método de hemaféreses e utilizados no Hospital das Clínicas e Hemocentro da Unicamp. Este documento visa uniformizar e informar os valores, doses e volumes necessários para a elaboraçäo de um concentrado de células progenitoras periféricas que permitam enxertamento eficaz, seguro e duradouro, bem como as definiçöes dos controles e parâmetros necessários. Säo apresentados os critérios de inclusäo, tanto para doadores normais alogênicos como para pacientes que faräo doaçäo para o transplante autólogo; os cuidados necessários para garantir a segurança dos procedimentos, bem como as condutas nas reaçöes. Säo apresentadas as rotinas técnicas utilizadas nos equipamentos disponíveis em nossa instituiçäo.