You can easily find other studies by googling microneedling and hair. There are two Dhurat studies (2013 en 2015), there is another Indian one: https://pubmed.ncbi.nlm.nih.gov/30886475/
There is a Chinese one, there is one comparing two needling depths. There is one about mice... There is a study with an overview of the literature... Just the ones I remember off the top of my head
All easy to find.