Cell culture studies on human nerve sheath tumors Kharbanda, Kusum; Dinda, Amit K.; Sarkar, Chitra ...
Pathology,
1994, 19940000, 1994-Jan, 1994-00-00, 19940101, Volume:
26, Issue:
1
Journal Article
Peer reviewed
The main controversy about nerve sheath tumors (NSTs) has been their histogenesis, A Schwann cell origin has been proposed by many investigators for both schwannomas and neurofibromas. However ...Erlandson and Woodruff1 observed that while schwannomas appeared to be composed predominantly of Schwann cells, neurofibromas consisted of mainly perineurial cells. In addition, variable numbers of fibroblast-like cells and intermediate cells also have been reported in the 2 lesions. Whether these represent distinct cell types or variants of Schwann cells is still debatable. In an attempt to solve this controversy, the present study was undertaken to observe the morphology and the behaviour of these tumors in culture. These studies showed that all nerve sheath tumors are basically of Schwann cell origin and that intermediate cells and fibroblasts are variants of Schwann cell. Tissue culture studies done chiefly on schwannomas showed that the morphological features of schwannomas are preserved in 'in vitro culture' condition and therefore the difference between neurofibroma and schwannoma appears to be due to inherent differentiating property of the Schwann cells along with some environmental stimulus.
This study was undertaken to investigate in-vivo proliferative potential of neoplastic cells in 66 cases of gliomas of different histological types following peroperative intravenous infusion of ...bromodeoxyuridine (BrdU). Histological typing according to the recent modification of WHO classification did not often correlate with in-vivo cell kinetics. Among the different morphological features used for the classification, necrosis, mitosis, increased cell density and increased endothelial cell proliferation showed good correlation with tumor cell labelling index (LI) (p < 0.01-p < 0.001). A preliminary follow-up study of 36 cases for a period ranging from 9 to 36 mths suggested the possibility that higher in-vivo tumor cell LI might be associated with an early recurrence. Thus in vivo BrdU LI may supplement the histological classification of gliomas and together they may help in a better assessment of their growth rate, degree of malignancy and biological behaviour which in turn facilitate the planning of therapeutic management for individual cases.
Astrocytomas of different grades of malignancy were cultured as primary explant and their sequential growth pattern, glial fibrillary acidic protein (GFAP) expression and labelling index (LI) using ...bromodeoxyuridine (BrdU) were assessed and correlated with the grade of malignancy of the original tumor tissue. Low-grade astrocytomas showed patterns of growth that diverged from anaplastic astrocytomas and glioblastoma multiforme. The GFAP expression decreased with increasing time in culture in all astrocytomas irrespective of the grading. Maximum GFAP was, however, expressed in the morphologically well-differentiated stellate cells. Contrary to expectations, lower BrdU LI was observed in gliobastoma multiforme in comparison to low-grade astrocytomas, which suggests some unidentified mechanism of differentiation in vitro for astrocytomas of higher grade of malignancy. Hence, in contrast to reported literature on the prognostic value of studies on primary cultures, the present study cautions the extrapolation of the in vitro findings for astrocytomas.
The present study was undertaken to evaluate the sequential BrdU-LI at weekly intervals upto four weeks in 18 primary explant cultures of meningiomas. This revealed three distinct patterns of growth ...which could be arbitrarily defined as 'degenerating' (group I), 'proliferating' (group II) and 'adaptive' (group III) types. Interestingly two cases of malignant and two of recurrent meningiomas fell into the 'degenerating' group I pattern. The possible explanations for the observed relatively higher in vitro LI values compared to lower in vivo values as reported in the literature and the theoretical implications of the three distinct patterns of sequential LI values are discussed.
In-vivo cell kinetics study following peroperative intravenous infusion of bromodeoxyuridine (BrdU) was done in 10 cases of primitive neuroectodermal tumors (PNET) and 44 nonglial tumors of different ...histological types. The histological features usually regarded as indicators of aggressive behaviour were examined in these tumors and correlated with in-vivo labelling index (LI). In the case of meningiornas, increased cellularity, pleomorphism and mitosis had no correlation with LI. Benign non-recurrent meningiomas usually showed LI 5 1% (mean 0.6±0.3%) whereas recurrent and malignant meningioma showed higher LI (mean 2.6±0.5% and 2.8±0.4% respectively). Follow-up study suggested that meningiomas having benign histological appearance with LI > 1% might have increased chance of recurrence. In cases of PNETs among different histological features, mitosis and differentiation seemed to be related to the biological behaviour. Astrocytic differentiation was associated with lower rate of proliferation. In pituitary adenomas different hormone producing and null cell adenomas showed similar low proliferative potential (0.6±0.3%). Benign nerve sheath tumors, craniopharyngioma and choroid plexus papilloma showed low in-vivo LI of less than 1%.
Thus the present study revealed the inadequacies of routine histological examination in assessing the aggressiveness of the nonglial tumors, especially rneningiomas. In-vivo LI may be a good supplement to histological diagnosis as well as helping to assess the prognosis and accordingly the management of individual cases.
We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes of the physics of inflation. We focus on the prospects for using CMB measurements to ...differentiate various inflationary mechanisms. In particular, a detection of primordial B-mode polarization would demonstrate that inflation occurred at a very high energy scale, and that the inflaton traversed a super-Planckian distance in field space. We explain how such a detection or constraint would illuminate aspects of physics at the Planck scale. Moreover, CMB measurements can constrain the scale-dependence and non-Gaussianity of the primordial fluctuations and limit the possibility of a significant isocurvature contribution. Each such limit provides crucial information on the underlying inflationary dynamics. Finally, we quantify these considerations by presenting forecasts for the sensitivities of a future satellite experiment to the inflationary parameters.
