How to write an email to request a dataset to a professor
Professors are just normal humans, even at MIT. Be friendly and brief. How about this:

Subject:


  Request for dataset used in [article name]


Body:


  Dear Professor [last name],
  
  on page [page number] of the article "[article name]" you are referring to a dataset consisting of [elements of dataset]. I am currently working on _____ and would like to ask if you could send me this dataset for further analysis as it would help me [benefit for you, e.g. "verify your results"].
  
  Thank you,
  
  [your first name] [your last name]