Human umbilical cord CD146 mesenchymal stem cells(Sanyoulikang)

1. Primary Objective: To evaluate the safety and tolerability of intravenous human umbilical cord CD146 mesenchymal stem cell injection in participants with ischemic stroke, and to explore the maximum tolerated dose (MTD) or dose-limiting toxicity (DLT) of human umbilical cord CD146 mesenchymal stem cell injection in participants with ischemic stroke. 2. Secondary Objective: To evaluate the preliminary efficacy of intravenous human umbilical cord CD146 mesenchymal stem cell injection in participants with ischemic stroke, using NIHSS scores and other methods to assess efficacy, and to provide a basis for selecting the investigational drug dosage in subsequent confirmatory clinical trials.