Elimination of clonogenic stem cells from human multiple myeloma cell lines by a plasma cell-reactive monoclonal antibody and complement

The monoclonal antibody (MoAb) MM4 reacts with human multiple myeloma (MM) cell lines and bone marrow from patients with plasma cell dyscrasias but not with normal peripheral blood or bone marrow cells. Treatment with MM4 and rabbit complement (C') was cytotoxic to the plasma cell-derived cell lines GM 1312, RPMI 8226, and ARH-77, as demonstrated by chromium release microcytotoxicity and trypan blue exclusion assays. The same treatment eliminated greater than 99% of clonogenic myeloma stem cell colony formation of these cell lines, with less than 20% inhibition of normal human bone marrow pleuripotent progenitor colony formation in vitro. As an experimental model to explore the efficacy of MM4 + C' in purging MM-involved bone marrow, normal marrow cells were mixed with RPMI 8226 or GM 1312 cells in the ratio of 90:10 or 50:50 (marrow:myeloma cells). Colony growth assays indicated that MM4 + C' eliminated at least 2 logs of clonogenic myeloma stem cells in both 90:10 and 50:50 preparations, while sparing the majority of normal marrow progenitors (inhibition of CFU-C:10% to 13%; BFU-E:0%). The selectivity of MM4-mediated cytotoxicity may be useful for eliminating myeloma clonogenic stem cells from bone marrow of patients with multiple myeloma.     

Limitations of flow cytometry in the analysis of CDIalHLADR+ human oral mucosal Langerhans cells

Suspensions of human oral epithetial cells were stained with antibodies to CD la and HLADR conjugated with fluorochromes and analysed by flow cytometry with the aim of purifying double-labetled Langerhans cells, a population comprising approximatety 2% of the cell total. Whole suspensions had high levets of autofluorescence and a wide range of forward and right angle scatter properties. The mean percentage of CDIalHLADR+ cells was 2.I%, though the double-labetled cells did not form a discrete group and the percentages of positive cells using control antibodies were similar. Density gradient centrifugation prior to flow cytometry did not facilitate Langerhanr cell identification within the suspension. The results indicate flow cytometric analysis of minority cell populations (such as Langerhans cells) within oral epithetium is limited by the autofluorescence of physically heterogeneous keratinocytes, and emphasise the importance of controls in studies of oral epithetium which use this method.     

Acoustic neuroma (vestibular schwannoma). Treatment from a neurosurgical perspective

During the last century microsurgical approaches laid emphasis in descending order on preservation of life, total tumor excision and function. Today, the priority of microsurgery has changed to functional preservation. The management of vestibular schwannomas consists of observation, surgical resection, or radiation therapy. In recent years, there has been an increase in observation-only management for small tumors, or radiotherapy in the case of tumor progression. The number of surgical procedures is in decline, with surgery being reserved mainly for large tumors.     

Aberrant expression of retinoic acid signaling molecules influences patient survival in astrocytic gliomas

Undifferentiated cell populations may influence tumor growth in malignant glioma. We investigated potential disruptions in the retinoic acid (RA) differentiation pathway that could lead to a loss of differentiation capacity, influencing patient prognosis. Expression of key molecules belonging to the RA differentiation pathway was analyzed in 283 astrocytic gliomas and was correlated with tumor proliferation, tumor differentiation, and patient survival. In addition, in situ concentrations of retinoids were measured in tumors, and RA signaling events were studied in vitro. Unlike other tumors, in gliomas expression of most RA signaling molecules increased with malignancy and was associated with augmented intratumoral retinoid levels in high-grade gliomas. Aberrantly expressed RA signaling molecules included i) the retinol-binding protein CRBP1, which facilitates cellular retinoid uptake; ii) ALDH1A1, capable of activating RA precursors; iii) the RA-degrading enzyme CYP26B1; and iv) the RA-binding protein FABP5, which can inhibit RA-induced differentiation. In contrast, expression of the RA-binding protein CRABP2, which fosters differentiation, was decreased in high-grade tumors. Moreover, expression of CRBP1 correlated with tumor proliferation, and FABP5 expression correlated with an undifferentiated tumor phenotype. CRBP1 and ALDH1A1 were independent prognostic markers for adverse patient survival. Our data indicate a complex and clinically relevant deregulation of RA signaling, which seems to be a central event in glioma pathogenesis.     

MRI of the Perihemorrhagic Zone in a Rat ICH Model: Effect of Hematoma Evacuation

Background  Perihemorrhagic pathophysiology of spontaneous intracerebral hemorrhages (ICH) remains unclear. Recently, ischemic changes in the perihemorrhagic zone (PHZ) have been discussed as a potential source of secondary damage. In this study, we focussed on diffusion and perfusion characteristics of experimental ICH. Methods  Experimental ICH was induced with a double injection model in rats. In total, 49 animals were examined at three timepoints within 3.5 h after ICH with a 2.35T animal scanner. We investigated perihemorrhagic relative apparent diffusion coefficients (rADC) and relative mean transit time (rMTT). Animals were divided into 2 groups; controls (gr1, n = 27) and facilitated hematoma evacuation with recombinant tissue plasminogen activator (rt-PA) after the first of 3 imaging time points (gr2, n = 22). Diffusion (rADC) and perfusion (rMTT) characteristics were analyzed in 3 regions of interest surrounding the hematoma (ROI1–3). Results  Overall rADC and rMTT values in ROI3 (normal tissue) did not show any changes. There was mild edema—not ischemia—in ROIs1 and 2 at TP1 with rADC of 1.05–1.18 in both groups indicating vasogenic edema (not ischemia). This did not change with hematoma evacuation. There was mild (non-critical) perfusion reduction in ROIs1 and 2 at TP1, which disappeared after clot evacuation in group 2 (P < 0.05 for TP3). Multifactorial ANOVA showed a solid trend (0.06 < P < 0.1) for clot evacuation associated normalization of perfusion in ROIs 1 and 2 within and in between groups 1 and 2. Conclusions  We demonstrated vasogenic edema and mild perfusion reduction in the PHZ above the ischemic threshold. The existence of a perihemorrhagic “penumbra” indicating critically ischemic tissue analogous to ischemic stroke is unlikely.