Figure 5.

PTEN deletion induces axon and myelin regeneration after FN injury. A-D, M, In the absence of injury, βIII tubulin-positive numbers were identical between Ctr. and KO nerves. At 14 dpi, axon numbers in the FN decreased in Ctr. (C) but not as much in Pten KO animals (D). M, Axon numbers per 0.03 mm² nerve area. Because of excess connective tissue and larger axon diameter, Pten KO animals have lower axon density in uninjured nerves. After injury, axon numbers decreased in both genotypes but recovered more quickly in PTEN-deficient animals. Dashed lines indicate axonal numbers in uninjured nerves in Ctr. (gray) or Pten KO (orange) animals (n = 6, 7, 6, 6, 6, 6, 9, 10 for each bar, respectively). R, Black dots in gray bars indicate Pten homozygous WT mice. Red dots indicate heterozygous mice. Black asterisks indicate significant differences of each bar to the uninjured (0 dpi) Ctr. bar, orange asterisks to the uninjured (0 dpi) Pten KO bar. E-H, N, Myelin was detected by MBP. In Pten KO nerves, numbers of properly myelinated axons (see inset in H) were increased compared with Ctr. nerves (G; quantified in N; n = 4, 6, 5, 5, 8, 7, 9, 10 for each bar, respectively). I-L, O, Myelination was stained with toluidine and more myelinated axons were observed after injury in KO (L) compared with Ctr. (K) animals (quantified in O; n = 0, 0, 5, 4, 4, 4, 5, 5 for each bar, respectively). Note the increased axon diameters in KO animals in the unlesioned condition (J). P-R, MNs differentiated from hiPSCs showed increased neurite outgrowth when treated the PTEN inhibitor SF1670 (Q) compared with control treatment with DMSO (P). R, Quantification of neurite outgrowth of MNs from tree different donors (D1-D3). M-O, Each dot indicates 1 animal. Data are mean ± SD. M-O, *p < 0.05; **p < 0.01; ***p < 0.001; two-sided Mann–Whitney test. R, *p < 0.05; **p < 0.01; ***p < 0.001; two-sided t test. Scale bars: A-H, 25 µm; I-L, 10 µm; P, Q, 50 µm.