Bus connection between Nairobi and Isiolo?

by Paul Gardner de Beville
(West Lafayette, Indiana, USA)

I am a student at an American University. I intend to travel to Kenya this summer, arriving in Nairobi at the end of June.

After a few days in Nairobi, I have to travel to the Northern town of Isiolo where I will be conducting some volunteer work.

Do you know if there's a bus connection from Nairobi to Isiolo?
Thank you so much for your help,
Paul Gardner de Beville