Assessment of the toxicity and carcinogenicity of double-walled carbon nanotubes in the rat lung after intratracheal instillation: a two-year study

Table 5 Cell proliferation and inflammation related parameters of the lung tissue at the final sacrifice^a

	Untreated	Vehicle	DWCNT 0.125 mg/rat	DWCNT 0.250 mg/rat	DWCNT 0.500 mg/rat	MWCNT^a 0.500 mg/rat
Granulation Tissue count/cm² mean ± S.D	0.9 ± 0.3	1.3 ± 0.6	50.9 ± 5.2**	118.9 ± 68.8***	365.1 ± 81.7***^,#	94.9 ± 35.3**
Macrophage count/cm² mean ± S.D	54.6 ± 16.4	75 ± 23.0	361.8 ± 53.4***	502.8 ± 59.1***^,#	479.1 ± 48.2***^,#	314.7 ± 91.6***
Alveolar PCNA index %	3.62 ± 1.7.3	4.48 ± 1.88	8.83 ± 4.28*	18.54 ± 7.35**	21.27 ± 10.57**^#	14.10 ± 10.29**
Visceral pleural PCNA index %	0.20 ± 0.28	0.36 ± 0.26	0.44 ± 0.17	1.40 ± 1.23	1.32 ± 0.72	15.20 ± 13.22**^$
Parietal pleural PCNA index %	2.00 ± 0.43	2.30 ± 0.66	2.00 ± 0.712	1.90 ± 0.77	2.60 ± 0.28	23.75 ± 32.56***^$
Pulmonary Collagen deposition %^b	13.04	8.50	13	18.15	20.47*	27*
Subpleural Collagen deposition % ^c	4.20	2.25	5.50	4.45	16.87	64.20***^$
CCL2 ng/mg lung protein mean ± S.D	0.77 ± 0.3	1.6 ± 0.87	6.67 ± 2.44***	8.40 ± 1.73^***,#	10.74 ± 1.94^***,##	5.20 ± 1.6***
CCL3 ng/mg lung protein mean ± S.D	0.58 ± 0.27	0.55 ± 0.16	0.71 ± 0.16^*,#	0.75 ± 0.21^*,#	0.74 ± 0.19^*,#	0.52 ± 0.12

^aIn the MWCNT-7 group, 16 animals died from malignant mesothelioma after 52 weeks and before 91 weeks. Because of the extensive invasion of the lungs by the mesotheliomas, these animals could not be assessed for the parameters shown in Table 5. Therefore, only the values obtained from the nine MWCNT-7 treated rats that survived for 91 weeks are shown in Table 5
^bResults are expressed as the percentage area of pulmonary collagen deposition/total alveolar tissue area
^cResults are expressed as the percentage area of subpleural collagen deposition/total pleural tissue area
*,**,***Significantly increased from the Vehicle at p < 0.05, 0.01, 0.001 respectively
^#,##Significantly increased compared to MWCNT-7 at p < 0.05, 0.01 respectively
^$Significantly increased in compared to DWCNT groups: p < 0.01

ISSN: 1743-8977