Acute Myocardial Infarction With ST Segment Elevation

The goal of this phase IIc clinical trial is to learn if recombinant human thymosin beta 4 injection (NL005) works to treat heart damage in people who have had a serious type of heart attack called ST-segment elevation myocardial infarction (STEMI) and have been treated with emergency percutaneous coronary intervention (PCI, a procedure to open the blocked artery). It will also learn about the safety of NL005. The main questions it aims to answer are: * Does NL005 lower the size of permanent heart muscle damage measured by cardiac magnetic resonance (CMR) scan 90 days after treatment? * What medical problems do participants have when taking NL005? Researchers will compare two different doses of NL005 to a placebo (a look-alike substance that contains no drug) to see if NL005 works better to reduce heart damage caused by the heart attack. Participants will: * Receive NL005 or placebo through a vein within 4 hours after the PCI procedure, then once a day for 7 days * Stay in the hospital for the first week for monitoring, blood draws, and electrocardiograms (heart tracings) * Have a CMR scan on Day 6 and Day 90 to measure the size of the heart injury * Return to the hospital for checkups on Day 30 and Day 90 * Be contacted by the study team (by phone or online) 3 times during the first year and come back to the hospital on Day 360 to check long-term recovery

The goal of this observational study is to learn if the novel biomarker Heat shock protein 47 (HSP47) can be used as a prognostic marker for vascular disease in people with acute venous thromboembolism (VTE), myocardial infarction (AMI) or ischaemic stroke compared to healthy volunteers. The main questions it aims to answer are: 1. Are platelet levels of HSP47 higher in patients with acute VTE, AMI or stroke, compared to healthy volunteers. 2. Does platelet levels of HSP47 remain elevated in patients with acute thrombotic events compared to healthy volunteers at 3 and 12-months of follow-up. 3. Are platelet levels of HSP47 postively associated with platelet function and negatively associated with fibrinolytic capacity in patients with an acute thrombotic event. Participants with VTE, AMI or stroke will be giving a blood sample at diagnosis and again after 3 and 12 months of follow-up. Healthy volunteers will be giving a blood sample once.