Heterogeneity of pituitary adenoma cell subpopulations from acromegalic patients obtained by Percoll density gradient centrifugation

Low-stress Microfluidic Density-gradient Centrifugation for Blood Cell Sorting

Density gradient centrifugation exploits density differences between different blood cells to accomplish separation of peripheral blood mononuclear cells (PBMCs) from polymorphonuclear (PNM) cells, and erythrocytes or red blood cells (RBCs). While density gradient centrifugation offers a label-free alternative avoiding the use of harsh lysis buffers for blood cell isolation, it is a time-consuming and labor-intensive process during which blood cells are subject to high-levels of centrifugal force that can artifactually activate cells. To provide a low-stress alternative to this elegant method, we miniaturized and automated this process using microfluidics to ensure continuous PBMCs isolation from whole blood while avoiding the exposure to high-levels of centrifugal stress in a simple flow-through format. Within this device, a density gradient is established by exploiting laminar flow within microfluidic channels to layer a thin stream of blood over a larger stream of Ficoll. Using this approach we demonstrate successful isolation of PBMCs from whole blood with preservation of monocytes and different lymphocyte subpopulations similar to that seen with conventional density gradient centrifugation. Evaluation of activation status of PBMCs isolated using this technique shows that our approach achieves minimal isolation process induced activation of cells in comparison to conventional lysis or density gradient centrifugation. This simple, automated microfluidic density gradient centrifugation technique can potentially serve as tool for rapid and activation-free technique for isolation of PBMCs from whole blood for point-of-care applications.

Prolactin presents in all pituitary tumors of acromegalic patients

Twenty-two consecutive cases of adenoma in acromegalic patients were studied immunohistochemically. All the tumors contained prolactin (PRL)-reactive cells (3% to 53% of the total number of tumor cells) as well as growth hormone (GH)-reactive cells (4% to 74% of the total number of tumor cells). All acromegalic cases studied were thus plurihormonal adenomas containing GH and PRL; no pure GH cell adenoma was present. Twenty cases were further examined at the ultrastructural level in conjunction with postembedding double-labeling immunoelectron microscopy; 15 of these cases were diagnosed as mixed GH cell-PRL cell adenomas. The previously diagnosed pure GH cell adenomas possibly may have contained PRL cells and thus should be considered as mixed GH cell-PRL cell adenomas. Mammosomatotroph adenomas were rare in this series. Double-labeling immunoelectron microscopy, using protein A gold particles of two different sizes, greatly facilitated the distinction among GH, PRL, and mammosomatotroph cells.

TRH-Gly, a precursor of TRH, alters GH secretion in acromegaly

We explored effects of a precursor of thyrotropin (TSH)-releasing hormone (TRH), TRH-Gly, on growth hormone (GH) secretion in acromegaly. Intravenous injection of TRH-Gly produced a profound increase in GH secretion in eight, decrease in two, and no response in five out of a total fifteen patients. The magnitude of GH responsiveness to TRH-Gly was significantly correlated with that induced by TRH (r = 0.824, P less than 0.01). In contrast, TRH-Gly did not induce secretion of TSH or prolactin. The present data suggest that TRH-Gly may participate in regulating GH secretion in some patients with acromegaly and that TRH-Gly-induced GH secretion may be due at least in part to TRH-associated mechanisms underlying GH secretion.