RecruitingDrug trialHetrombopag in Promoting Platelet Engraftment After Auto-HSCT in Children With NeuroblastomaThe goal of this clinical trial is to learn if hetrombopag promotes platelet engraftment in neuroblastoma children undergoing autologous hematopoietic stem cell transplantation. The main question it aims to answer is: · Does drug hetrombopag promote platelet engraftment? Participants will take hetrombopag every day for 6 weeks or until platelet \> 100\*10\^9/L.