Abstract
Desmoplakin cardiomyopathy (DSP-CM) was recently described as a distinct form of cardiomyopathy (PMID: 37048743). Pathogenic variants in the desmosomal DSP gene, predispose to severe phenotypes with left ventricular involvement, extensive fibrosis, high arrhythmic risk and recurrent myocardial injury (PMID: 37048743). We have previously demonstrated that the DSP antisense lncRNA (DSP-AS1), which partially overlaps the DSP locus, can reduce DSP protein amounts (PMID: 40736537). We have also reported that in healthy hiPSC-derived cardiomyocytes (iCMs) a specific DNA antisense oligonucleotide (Gapmer), named LNA2, can significantly increase DSP transcript levels through the downregulation of DSP-AS1 (PMID: 40736537). This indicates that DSP-AS1 could be a potential therapeutic target for DSP-CM. Here we report preliminary data obtained in a DSP-CM patient-derived hiPSC line (DSP-CM-hiPSCs) carrying a heterozygous nonsense mutation, causing a condition of DSP haploinsufficiency. First, we have differentiated the DSP-CM-hiPSCs in iCMs, cardiac fibroblasts (iCFs), and endothelial cells (iECs) with the final aim to create 3D advanced models for DSP-CM. The first microtissues and engineered heart tissues were then created. The expression of DSP-AS1 and DSP was confirmed by droplet digital PCR in all three differentiated cell types. Notably, the detection of both transcripts in iECs represents a novel finding, as their expression had not previously been documented in these cells. While DSP-AS1 and DSP expression levels were similar in iCMs and iCFs, both transcripts were significantly lower in iECs, suggesting that iCM and iCFs could contribute more to the pathology than iECs. Importantly, the LNA2 treatment on DSP-CM-iCMs showed a significant decrease of DSP-AS1 with a subsequent restoring of DSP transcript level. These preliminary data indicate that inhibiting DSP-AS1 with LNA2 may effectively restore the amount of DSP transcript in DSP-CM-iCMs. Further molecular and electrophysiological experiments are necessary to confirm the effectiveness of this approach for addressing the DSP haploinsufficiency in iCMs, iCFs and iECs, as well as in the 3D models.
Fundings: this project is funded by the Autonomous Province of Bolzano-Bozen - South Tyrol.