Double strand break (DSB) repair primarily occurs through 3 pathways: non-homologous end-joining (NHEJ), alternative end-joining (Alt-EJ), and homologous recombination (HR). Typical methods to measure pathway usage include integrated cassette reporter assays or visualization of DNA damage induced nuclear foci. It is now well understood that repair of Cas9-induced breaks also involves NHEJ, Alt-EJ, and HR pathways, providing a new format to measure pathway usage. Here, we have developed a simple Cas9-based system with validated repair outcomes that accurately represent each pathway and then converted it to a droplet digital PCR (ddPCR) readout, thus obviating the need for Next Generation Sequencing and bioinformatic analysis with the goal to make Cas9-based system accessible to more laboratories. The assay system has reproduced several important insights. First, absence of the key Alt-EJ factor Pol θ only abrogates ∼50% of total Alt-EJ. Second, single-strand templated repair (SSTR) requires BRCA1 and MRE11 activity, but not BRCA2, establishing that SSTR commonly used in genome editing is not conventional HR. Third, BRCA1 promotes Alt-EJ usage at two-ended DSBs in contrast to BRCA2. This assay can be used in any system, which permits Cas9 delivery and, importantly, allows rapid genotype-to-phenotype correlation in isogenic cell line pairs.

In some vein of galen aneurysmal malformation (VGAM) patients, transvenous embolization (TVE) is an attractive option, but its safety is unclear. Here we report the first two VGAM patients treated using the Chapot “pressure cooker” technique (ChPC). Methods Two patients, one 5-year-old and one 7-year-old, both presented with congestive heart failure in the newborn period and were subsequently treated in the newborn period with multiple, staged TAEs with n-BCA for choroidal VGAMs. Results We achieved progressive reduction in shunting and flow but were unable to accomplish complete closure of the malformation: in both patients, a small residual with numerous perforators persisted. The decision was made to perform TVE using the CHPC. In this technique, a guiding catheter is placed transjugular into the straight sinus (SS). One or two detachable tip microcatheters are advanced to the origin of the SS. Another microcatheter is advanced and the tip placed between the distal marker and the detachment zone of the former. Coils and n-BCA are used to prevent reflux of Onyx. Conclusions In this study, we recognized two important factors of traditional VGAM treatment that may cause interventionalists to consider the ChPC to treat VGAM: (1) without liquid embolic, deployed coils may not occlude the fistula entirely. (2) There is the concern of causing delayed bleeding should the arterial component of the fistula rupture. ChPC ameliorates these issues by offering complete closure of the fistula with liquid embolic material in TVE.

BackgroundTreatment of vein of Galen malformations (VOGMs) has improved greatly since the inception of endovascular treatment. Transvenous embolization (TVE) is an attractive option to achieve complete obliteration.ObjectiveTo review the literature on TVE of VOGM and then analyze our practice’s unique experience and evolving treatment strategies over 30 years.MethodsA retrospective review of our clinical database for patients with the diagnosis of VOGM treated between January 2004 and August 2021 was performed. A literature review of 49 relevant articles was also carried out.ResultsTVE in VOGM has evolved with initial introduction as a transtorcular (TT) approach, which then lost favor to transarterial embolization (TAE). TAE has been considered the more favorable approach in most high-volume centers. In more recent times, the transvenous embolization (TVE) approach has been revisited as a last treatment to achieve a cure after a series of TAE treatments. We presently favor beginning treatment with staged TAE to reduce flow to the lesion and, importantly, shrink the draining vein. This then allows for the performance of TVE with the Chapot pressure cooker technique (CPCT) with coils and liquid embolic embolization.ConclusionsTT TVE itself carries a high degree of risk and is most highly associated with long-term morbidities and mortality. Traditional transfemoral/transjugular TVE approaches are safe and effective in simple fistulas with a small venous pouch; however, we believe that the CPCT is the safest technique as a last-stage treatment for its security in avoiding reflux and obtaining occlusion of the small perforators.

Background: Endovascular aneurysmal coiling is a preventative alternative to clipping to avoid aneurysmal rupture. In the literature and our own experience, some common coiling challenges which arise include: (1) microcatheter kickback, (2) detachment zone rigidity, (3) intrasaccular compartmentalization of coils on deployment, and (4) attainability of high-density and effective packing with as few coils as possible. Methods: We retrospectively reviewed a consecutive case series of 15 intracranial aneurysm patients who received Kaneka i-ED Coils since their initial use in our practice (December 2020) till May 2022. Results: Of the 14 saccular aneurysm patients treated with i-ED coils, 2/14 (14.3%) achieved a Raymond-Roy (RR) score of 3A (internal remnant), 4/14 (28.6%) achieved RR 2 (slight neck remnant) and 8/14 (57.1%) achieved RR 1. One MoyaMoya patient (5.9%) with a fusiform aneurysm also achieved a complete occlusion by parent artery takedown in this series. Aneurysm volumes ranged from 8.15 mm 3 to 315.5 mm 3 with an average packing density of 36.23% and a standard deviation 8.87%. At 30 days, most of our cohort scored a 0 on the modified Rankin scale (mRS) (11/15), with two patients scoring at an mRS score of 1, one at an mRS score of 4, and one at an mRS score of 6. Low-memory shape, coil cases achieved a significantly higher packing density (P < 0.01) and PD/Coils-used ratio (P < 0.05) than other cases in our practice. Conclusion: Our initial experience with i-ED coils has shown that they are a feasible strategy in a number of differently sized and shaped aneurysms. While fewer coils overall were not a statistically significant finding in this study, the future studies with larger cohorts are necessary and in progress.