NG2-proteoglycan-dependent contributions of oligodendrocyte progenitors and myeloid cells to myelin damage and repair

Table 1 Effects of cell-type-specific ablation of NG2 on cell and axon biology

Row		Control	OPC-NG2ko	My-NG2ko
	Sham-operated animals
1	Number of Olig2⁺ cells	115.27 ± 3.8	111.02 ± 5.7	117.63 ± 5.4
2	Number of Olig2⁺/PDGF-Rα⁺ OPCs	14.55 ± 1.7	12.31 ± 2	14.46 ± 3.5
	1 week after demyelination
3	Number of Iba1⁺ macrophages/microglia	117.19 ± 22.3	120.1 ± 28.1	39.64 ± 19.8**
4	Number of Olig2⁺/PDGF-Rα⁺ OPCs	42.92 ± 1.5	32.4 ± 1.7***	23.02 ± 7.2***
5	Mitotic index of Olig2⁺/PDGF-Rα⁺ OPCs (%)	22.91 ± 3.5	13.49 ± 1.5**	11.93 ± 2.1***
	6 weeks after demyelination
6	Number of APC⁺ oligodendrocytes	62.14 ± 6.7	44.48 ± 8.6*	43.17 ± 4.1**
7	Well-myelinated axons	1056 ± 133	480 ± 128**	499 ± 80**
8	Myelin thickness (g value)	0.745 ± 0.089	0.861 ± 0.099***	0.87 ± 0.065***
9	Number of NF-positive axons
	Small: diameter < 1 μm	1103 ± 60	660 ± 66***	812 ± 85**
	Medium: diameter = 1–2.5 μm	201 ± 29	135 ± 10*	118 ± 14*
	Large: diameter > 2.5 μm	18 ± 3	6 ± 1**	8 ± 2*

The key parameters for Olig2/PDGFRα-positive OPCs, Iba1-positive macrophages/microglia, and APC-positive oligodendrocytes were quantified in lesions in control, OPC-NG2ko, and My-NG2ko mice (n = 4 for each group) from 1 to 6 weeks after lysolecithin injection. The rationale for using Iba1 labeling in place of CD18 labeling was to attempt quantification of both activated myeloid cells inside lesions and non-activated myeloid cells remaining outside lesions. However, in this set of results, we have only examined Iba1-positive cells within lesions, in parallel to analyses of lesional CD18-positive cells in other parts of the text. Values represent means ± S.D. Statistically significant differences evaluated by ANOVA and t-test are indicated by ^* P < 0.05, ^** P < 0.01, and ^*** P < 0.001 when values were compared between controls and NG2 conditional knockout mice at the same time point. Cell and axon numbers are determined in 100,000-μm³ volumes.