RESUMO
BACKGROUND: The existence of pituitary stem cells in the adult pituitary gland is supported by such findings as postnatal proliferation, differentiation based on environmental alterations, and development of hormone-producing cells after specific lesions in the pituitary. OBJECTIVE: We discuss which cells in the adult pituitary gland might play a role as pituitary stem cells, the potential for these cells to initiate pituitary adenomas, and possible future clinical implications. METHODS: We reviewed the English literature in search for scholarly articles related to stem cells in the adult pituitary, cells with embryonic profile in the adult gland, mitogenic characteristics of adult pituitary cells, and pituitary adenoma oncogenesis. RESULTS: We identified and analyzed 135 articles related to pituitary stem cells and pituitary development published since 1965. Stem cell characteristics, including renewal, proliferation abilities, and the presence of stem cells markers, have been demonstrated by adult pituitary cells from mammals. However, the proliferation ability observed so far is limited, and the potential of differentiation into hormone-secreting cells remains to be conclusively proven. Stem cell markers have been detected in animal models of pituitary tumorigenesis; however, a direct connection has not been demonstrated. CONCLUSION: Research into the capacity of "pituitary stem cells" to differentiate in vitro and in vivo will clarify the mechanisms for regulation of these cells. As pituitary stem cells are better understood, clinical applications like the treatment of pituitary adenomas and the implantation of pituitary stem cells for hormonal deficiencies may be developed.
Assuntos
Adenoma/patologia , Células-Tronco Adultas/citologia , Diferenciação Celular/fisiologia , Linhagem da Célula/fisiologia , Hipófise/citologia , Neoplasias Hipofisárias/patologia , Adenoma/terapia , Células-Tronco Adultas/fisiologia , Animais , Biomarcadores/análise , Biomarcadores/metabolismo , Proliferação de Células , Humanos , Hipófise/fisiologia , Neoplasias Hipofisárias/terapia , Transplante de Células-Tronco/métodos , Transplante de Células-Tronco/tendênciasRESUMO
Pituitary tumors are challenging tumors in the sellar region. Surgical approaches to the pituitary have undergone numerous refinements over the last 100 years. The introduction of the endoscope have revolutionized pituitary surgery. The aim of this study is to report the results of a consecutive series of patients undergoing pituitary surgery using a pure endoscopic endonasal approach and to evaluate the efficacy and safety of this procedure. We reviewed the data of 228 consecutive patients who underwent endonasal transsphenoidal adenoma removal over an 10-year period. Pre- and post-operative hormonal status (at least 3 months after surgery) were analyzed and compared with clinical parameters presented by the patients. Tumor removal rate, endocrinological outcomes, and complications were retrospectively assessed in 228 patients with pituitary adenomas who underwent 251 procedures between December 1998 and December 2007. There were 93 nonfunctioning adenomas, 58 growth hormone-secreting, 41 prolactin-secreting, 28 adrenocorticotropin hormone secreting, 7 FSH-LH secreting and 1 thyroid-stimulating hormone-secreting adenomas. Gross total removal was achieved in 79.3% of the cases after a median follow-up of 61.5 months. The remission results for patients with nonfunctioning adenomas was 83% and for functioning adenomas were 76.3% (70.6% for GH hormone-secreting, 85.3% for prolactin hormone-secreting, 71.4% for ACTH hormone-secreting, 85.7% for FSH-LH hormone-secreting and 100% for TSH hormone-secreting), with no recurrence at the time of the last follow-up. Post-operative complications were present in 35 (13.9%) cases. The most frequent complications were temporary and permanent diabetes insipidus (six and two cases, respectively), syndrome of inappropriate antidiuretic hormone secretion (two cases) and CSF leaks (eight cases). There was no death related to the procedure in this series. The endoscopic endonasal approach for resection of pituitary adenomas, provides acceptable results representing a safe alternative procedure to the microscopic approach. This less invasive method, associated with a small number of complications, provides excellent tumor removal rates and represents an important tool for the achievement of good results in the pituitary surgery, mainly for the complete removal of large adenomas.