Odds are, the fish oil used will be ethyl ester oil. Why? Natural triglyercide oil is not very shelf stable, is not concentrated so it has lower levels of EPA and DHA, and it can contain impurities such as heavy metals, PCBs, and dioxins. Ethyl ester oil is concentrated and is also filtered (molecularly distilled) to remove impurities. Hopefully it is not synthetic triglyceride oil - that’s fish oil that has been processed to ethyl ester oil then reprocessed into synthetic triglyceride oil - this oil has the lowest bioavailability of the three types.
But recall that the study involved directly injecting the oil into the central vein of anesthetized mice and focused only on the lowering the arterial blood pressure. It is ignoring any other benefit (not knocking on the research - it is expected of this type of study); reduction in LDL, increase of HDL, reduced blood glucose levels, improvement of absorption of EPA and DH.
Ingesting fish oil is also quite different than injecting it straight into your veins. This just doesn’t occur in nature and I hope you are not injecting supplements directly into a vein. Studies show the bioavailability via digestion is highest from eating fish, lower for natural triglyercide oil, lower again for Ethyl ester oil, and once again lower for synthetic triglyceride oil. So all supplements regardless of the source will not be as good for you as eating a fatty fish like salmon, anchovy, herring, or mackerel.
If you want the best benefits, you should be eating fish. Focusing on a single aspect of any supplement will always give you concerns.