a, qPCR of OPCs reveals a loss of Lmnb1 expression and gain of Lmna expression with ageing. Values represent averages of OPCs from N = 3 animals for each time point and are the log 2 change in cycle threshold (∆CT) values normalized to the expression of Tbp, which is expressed in cells throughout the body. b, Representative images of in vivo cerebellar grey-matter cryosections from N = 3 biological replicates confirm changes in nuclear lamina that occur with ageing. Scale bar, 50 µm. White arrows highlight representative Ng2-expressing OPCs at each age. c, Representative western blot of Lamin B1 (LMNB1) and Lamin C (LMNC) proteins from freshly isolated OPCs of different ages confirms the qPCR data. ACTB is actin-β, a reference protein; p4 to p810 are protein fragments. Similar results were obtained for N = 3 biological replicates for each age group. d, RNA-sequencing data for nuclear Lmnb1 and Lmnb2 in neonatal and aged OPCs show low levels of expression of Lmnb2 in both age groups. e, f, Western blot quantifications of laminins from aged OPCs grown on soft and stiff hydrogels. g, Representative images from N = 3 biological replicates of changes in nuclear lamina in OPCs on hydrogels of different stiffnesses. Scale bar, 50 µM. h, Representative image from N = 3 biological replicates of red fluorescent protein (RFP)-conjugated non-targeting siRNA shows a high efficiency of siRNA transfection in vitro. Scale bar, 100 µM. i, qPCR on adult OPCs 48 hours after transfection with siRNAs, showing efficient knockdown of Lmna and Fak1 (also known as Ptk2) expression. Values represent averages of OPCs from N = 3 animals and are the log 2 ∆∆CT values normalized to Tbp. j, k, Representative images and quantifications of the proliferation of N = 3 aOPCs in growth factors on stiff hydrogels following transfection with siRNAs for Lmna and Fak1. Scale bars, 50 µM. l, A representative image from N = 3 biological replicates of GFP-encoding mRNA in neonatal OPCs shows high-efficiency transfection. Scale bar, 100 µM. m, Representative image from N = 3 biological replicates, showing efficient transfection, high translation and proper protein localization of Lamin C in aOPCs. Scale bar, 25 µM. n, qPCR data five days post-transfection from RNA isolated from transfected OPCs. Means represent log 2 ∆∆CT means across N = 2 biological replicates. o, p, Representative images and quantifications of N = 3 replicates in nOPCs on soft hydrogels show loss of proliferative capacity 120 hours after Lmnc mRNA overexpression but not after GFP overexpression. Scale bar, 100 µM.