Biology subjects

Zaw Thin, M.

Publications and source records attributed to Zaw Thin, M..

3 recordsLinked to original sources

bioRxiv2022

PKN2 deficiency leads both to prenatal congenital cardiomyopathy and defective angiotensin II stress responses.

BackgroundThe protein kinase PKN2 is required for embryonic development, and PKN2 knockout mice die as a result of failure in expansion of mesoderm tissues, cardiac development and neural tube closure. In the adult, cardiomyocyte PKN2 and PKN1 (in combination) are required for cardiac adaptation to pressure-overload. The role of PKN2 in contractile cardiomyocytes during development and its role in the adult heart remain to be fully established. MethodsWe used mice with cardiomyocyte-directed knockout of PKN2 or global PKN2 haploinsufficiency. Cardiac function and dimensions were assessed with high resolution episcopic microscopy, MRI, micro-CT and echocardiography. Biochemical and histological changes were assessed. ResultsCardiomyocyte-directed PKN2 knockout embryos displayed striking abnormalities in the compact myocardium, with frequent myocardial clefts and diverticula, ventricular septal defects and abnormal heart shape. The sub-Mendelian homozygous knockout survivors developed cardiac failure. RNASeq data showed upregulation of PKN2 in patients with dilated cardiomyopathy, suggesting an involvement in adult heart disease. Given the rarity of homozygous survivors with cardiomyocyte-specific deletion of PKN2, this was explored using mice with constitutive heterozygous PKN2 knockout. Cardiac hypertrophy resulting from hypertension induced by angiotensin II was reduced in haploinsufficient PKN2 mice relative to wild-type littermates, with suppression of cardiomyocyte hypertrophy and cardiac fibrosis. ConclusionsCardiomyocyte PKN2 is essential for heart development and formation of compact myocardium, and is also required for cardiac hypertrophy in hypertension. Thus, PKN signalling may offer therapeutic options for managing congenital and adult heart diseases.

developmental biology↗

bioRxiv2019

89Zr-oxine labelling and PET imaging shows lung delivery of a cell/gene cancer therapy

PurposeMSCTRAIL is a new stem cell-based therapy for lung cancer, currently in phase I evaluation (ClinicalTrials.gov ref: NCT03298763). Biodistribution of cell therapies is rarely assessed in clinical trials, despite cell delivery to the target site often being critical to presumed mechanism of action. This preclinical study demonstrates that MSCTRAIL biodistribution dynamics can be detected non-invasively using 89Zr-oxine labelling and PET imaging, thus supporting use of this cell tracking technology in phase II evaluation.\n\nMethodsMSCTRAIL were radiolabelled with a range of 89Zr-oxine doses, and assayed for cell viability, phenotype and therapeutic efficacy post-labelling. Cell biodistribution was imaged in a mouse model of lung cancer using PET imaging and bioluminescence imaging (BLI) to confirm cell viability and location in vivo up to 1 week post-injection.\n\nResultsMSCTRAIL retained therapeutic efficacy and MSC phenotype at doses up to and above those required for clinical imaging. The effect of 89Zr-oxine labelling on cell proliferation rate was dose and time-dependent. PET imaging showed delivery of MSCTRAIL to the lungs in a mouse model of lung cancer, with PET signal correlating with the presence of viable cells as assessed by bioluminescence imaging, ex vivo autoradiography and matched fluorescence imaging on lung tissue sections. Human dosimetry estimates were produced using simulations and preclinical biodistribution data.\n\nConclusion89Zr-oxine labelling and PET imaging present an attractive method of evaluating the biodistribution of new cell-therapies, such as MSCTRAIL. This offers to improve understanding of mechanism of action, migration dynamics and interpatient variability of MSCTRAIL and other cell-based therapies.

cell biology↗

bioRxiv2019

Stem cell delivery to kidney via minimally invasive ultrasound-guided renal artery injection in mice

Cell-based therapies are promising treatments for various kidney diseases. However, the major hurdle in initiating therapeutic responses is the inefficiency of injection routes to deliver cells to the kidney parenchyma. Systemic injection, such as intravenous injection only delivers a small proportion of cells to the kidney. Whereas direct delivery, such as renal artery injection require surgical procedures. A minimally invasive renal artery injection was therefore developed to enhance cell delivery to kidney. In this study, luciferase expressing human adipocyte derived stem cells (ADSC) were labelled with gold nanorods (GNR) and injected into the renal artery using ultrasound guidance. The ADSCs were tracked using bioluminescence and photoacoustic imaging serially over 7 days. Imaging confirmed that the majority of signal was within the kidney, indicative of successful injection and that signal remained stable for 3 days. Histology showed co-localization of GNRs with ADSC staining throughout the kidney with no indication of injury caused by injection. These findings demonstrate that ultrasound-guided renal artery injection is feasible in mice and can successfully deliver a large proportion of cells which are retained within the kidney for 3 days. Therefore, the techniques developed here will be useful for optimising cell therapy in kidney diseases.

cell biology↗