Cellular radiosensitivity of a rat brain tumor

Summary.-The degree of non-neoplastic host-cell infiltration was assessed in 3 in vivo-in vitro tumour models commonly used in radiobiological studies: EMT6/Ro mammary carcinoma, 9L/Ro tumour and KHT sarcoma. While the 2 former tumour models have been shown to be moderately to highly immunogenic when grown s.c., the KHT sarcoma is apparently non-immunogenic. Using differential staining on single-cell suspensions from enzymatically dissociated solid tumours, all 3 tumour types were found to contain large proportions (3060%) of non-neoplastic host cells.The actual host-cell component found in the cell suspensions differed both in type and percentage for the 3 tumours studied. These host and neoplastic cells in the cell suspensions prepared from the solid tumours could readily be separated by centrifugal elutriation. After separation the clonogenic potential of the neoplastic cells was assessed, and was found to be higher than the clonogenic capacity of the unseparated cell suspension by a factor directly related to the host/neoplastic cell ratio. Even after the removal of the host cells, the clonogenic capacities of the neoplastic EMT6 and 9L tumour cells were lower than that of the corresponding in vitro sublines (,30 vs -75%). However, in the KHT sarcoma the removal of the host cell component raised the plating efficiency to .60°/,, which was similar to the value for the in vitro cell subline of this tumour.

Section: Animals and In Vivo Tumour Systemsmentioning

confidence: 99%

Cell subpopulations dispersed from solid tumours and separated by centrifugal elutriation

Siemann¹,

Lord²,

Keng³

et al. 1981

“…Using nitroimidazolebinding techniques, specifically the 2-nitroimidazole EF5 with (Leith et al, 1975;Wallen et al, 1980). These cells were originally obtained from Dr KT Wheeler (Bowman Gray School of Medicine, Winston Salem, NC, USA).…”

mentioning

confidence: 99%

Use of power Doppler ultrasound-guided biopsies to locate regions of tumour hypoxia

Evans

Laughlin²,

Pugh³

et al. 1997

Summary The purpose of this study was to determine whether power Doppler ultrasound techniques could be used to direct biopsies into tumour regions with relatively low red blood cell flux, and therefore preferentially sample regions that were relatively hypoxic. Subcutaneous 9L glioma rat tumours were biopsied using power Doppler ultrasound guidance. Immunohistochemical detection of the 2-nitroimidazole EF5 was performed to determine the presence and level of hypoxia in the biopsy samples. Comparisons between the power Doppler-determined red blood cell flux and EF5 binding were made. In seven out of eight tumours studied, power Doppler ultrasound allowed differentiation of a relatively hypoxic region from a relatively oxic region by localizing relatively low vs high red blood cell flux areas respectively. In one of these seven tumours, RBC flux was high in both biopsied sites and hypoxia was not present in either. In two of these seven tumours, hypoxia was present in each biopsy and both of the red blood cell flux measurements were low. In the eighth tumour, both the EF5 binding and the red blood cell flux measurements were low. In this tumour, low EF5 binding was due to the dominance of necrotic cells, which will not reduce or bind EF5 in the biopsy specimen. Using EF5-binding techniques, we have confirmed that regions of relatively low red blood cell flux are more hypoxic than those with relatively high red blood cell flux. Counterstaining specimens with haematoxylin and eosin allows differentiation of low EF5-binding regions due to oxia vs necrosis. These methods have clinical implications for the expanded use of power Doppler ultrasound as a means to direct tissue sampling when it is important to identify the presence of hypoxia.

“…Intracerebral (i.c.) tumours were obtained by implanting 5 x 103 exponentially growing 9L cells into the cerebrum of male Fisher 344 rats (Barker et al, 1973;Leith et al, 1975). Three to six intracerebral tumours weighing 70-150mg each were pooled together in each experiment to yield enough cells in each elutriated fraction for the cell survival measurements.…”

Section: Cell Lines and Implantation Conditionsmentioning

confidence: 99%

“…Following the irradiation, clonogenic cell survival in the various fractions was determined using in vivo to in vitro colony forming assays. The detailed procedures for both 9L and KHT cells have been described previously (Leith et al, 1975;Wheeler et al, 1984;Thomson & Rauth, 1974;Rosenblum et al, 1975). Since cell suspensions prepared from 9L or KHT tumours contain -40-60% non-neoplastic host cells , all cell survival values reported for solid tumours were corrected on the basis of differential counts performed on cytospin slides (Siemann et al, 1982 …”

Section: Irradiationmentioning

confidence: 99%

Comparison of tumour age response to radiation for cells derived from tissue culture or solid tumours

Keng¹,

Siemann²,

Wheeler³

1984

Summary Direct comparison of the cell age response of 9L and KHT tumour cells derived either from tissue culture or solid tumours was achieved. Cells from dissociated KHT and 9L tumours (the latter implanted either subcutaneously or intracerebrally) and cells from tissue culture were separated into homogenous sized populations by centrifugal elutriation. In both tumour models these homogeneous sized populations correspond to populations enriched at different stages of the cell cycle. The survival of these elutriated cell populations was measured after a single dose of Cs-137 gamma rays. For cells isolated from 9L solid tumours, there was little variation in radiosensitivity throughout the cell cycle; however, a very small but significant increase in resistance was found in late G, cells. This lack of a large variation in radiosensitivity through the cell cycle for 9L cells from solid tumours also was seen in 9L cells growing in monolayer tissue culture. When similar experiments were performed using the KHT sarcoma tumour model, the results showed that KHT cells in vitro exhibited a fairly conventional increase in radioresistance in both mid G, and late S. However, the cell age response of KHT cells from solid tumours was different; particularly in the late S and G2 + M phases. These data demonstrate that direct extrapolation of in vitro cell age responses to the in situ situation may not always be valid.