Independent director Jonathan Glenn has stepped up to chair the business on an interim basis and in a non-executive role rather than the executive capacity of his predecessor.
In a statement, the company said its board will review the position and further announcements will be made in “due course”.
Randeep Grewal, head of the nominations committee at the regenerative medicines business, thanked Samuel for his “commitment and contribution”, before welcoming Glenn to his new position.
“Jonathan brings with him a deep understanding of the healthcare industry and experience in leading companies through successful growth phases,” Grewal added.
“Jonathan's knowledge and leadership will be increasingly valuable as we look to secure the next stage of our commercial development."
Glenn was formerly chief executive of Consort Medical before its £505mln sale to Recipharm recently.