Isolation procedure and characterization of multipotent adult progenitor cells from rat bone marrow.

Multipotent adult progenitor cells (MAPCs) are adult stem cells derived from the bone marrow of mouse and rat and were described for the first time in 2002 (Jiang et al., Nature 418:41-49, 2002), and subsequently (Breyer et al., Exp Hematol 34:1596-1601, 2006; Jiang et al., Exp Hematol 30:896-904, 2002; Ulloa-Montoya et al., Genome Biol 8:R163, 2007). The capacity of rodent MAPC to differentiate at the single-cell level into some of the cell types of endoderm, mesoderm, and neuroectoderm germ layer lineages makes them promising candidates for the study of developmental processes. MAPC are isolated using adherent cell cultures and are selected based on morphology after a period of about 8-18 weeks. Here, we describe a step-by-step reproducible method to isolate rat MAPC from fetal and adult bone marrow. We elaborate on several aspects of the isolation protocol including, cell density and medium components, and methods for selecting and obtaining potential MAPC clones and their characterization.

Extraction force and cortical tissue reaction of silicon microelectrode arrays implanted in the rat brain.

Micromotion of implanted silicon multielectrode arrays (Si MEAs) is thought to influence the inflammatory response they elicit. The degree of strain that micromotion imparts on surrounding tissue is related to the extent of mechanical integration of the implanted electrodes with the brain. In this study, we quantified the force of extraction of implanted four shank Michigan electrodes in adult rat brains and investigated potential cellular and extracellular matrix contributors to tissue-electrode adhesion using immunohistochemical markers for microglia, astrocytes and extracellular matrix deposition in the immediate vicinity of the electrodes. Our results suggest that the peak extraction force of the implanted electrodes increases significantly from the day of implantation (day 0) to the day of extraction (day 7 and day 28 postimplantation) (1.68 +/- 0.54 g, 3.99 +/- 1.31 g, and 4.86 +/- 1.49 g, respectively; mean +/- SD; n = 4). For an additional group of four shank electrode implants with a closer intershank spacing we observed a significant increase in peak extraction force on day 28 postimplantation compared to day 0 and day 7 postimplantation (5.56 +/- 0.76 g, 0.37 +/- 0.12 g and 1.87 +/- 0.88 g, respectively; n = 4). Significantly, only glial fibrillary acidic protein (GFAP) expression was correlated with peak extraction force in both electrode designs of all the markers of astroglial scar studied. For studies that try to model micromotion-induced strain, our data implies that adhesion between tissue and electrode increases after implantation and sheds light on the nature of implanted electrode-elicited brain tissue reaction.

Multivariate analysis of ATR-IR spectroscopic data: applications to the solid-liquid catalytic interface.

It is demonstrated that attenuated total reflection infrared (ATR-IR) spectroscopy coupled with multivariate data analysis can be effectively used for in situ investigation of supported catalyst-liquid interfaces. Both formaldehyde adsorption/dissociation in water and acetonitrile adsorption in hexane on thin (ca 10 mum) films of 5 wt % Pt/gamma-Al(2)O(3) deposited on a germanium waveguide have been investigated. The multivariate analysis applies classical least squares (CLS) and partial least squares (PLS) methods to the ATR-IR data in order to correlate spectral changes with known sources of experimental variation (i.e., time, concentration of solution species, etc.). The formaldehyde adsorption experiments revealed no spectroscopic evidence for adsorbed molecular formaldehyde under the conditions examined. However, the dissociation product carbon monoxide was observed to form in atop configuration on Pt, likely on edges and terrace sites. Isotope labeling experiments suggest that a pair of peaks observed at 1990 and 2060 cm(-)(1) during treatments of Pt in H(2)-saturated water arise at least in part from nu(Pt)(-)(H) stretching of adsorbed atomic hydrogen. Acetonitrile was found to adsorb on the Pt catalyst by sigma-bonding of the CN group with the platinum, yielding apparent surface peaks that are almost identical to that observed in the liquid phase. A peak at 1641 cm(-)(1) was observed which was assigned to the adsorption of the CN group in a tilted configuration involving a combination of end-on and pi interaction with the surface. This species was found to be reactive toward hydrogen, suggesting that it might play a role in nitrile hydrogenation. The prospects of using this approach to examine solid-catalyzed liquid-phase reactions are discussed in light of these findings.