- Abingworth Management Inc
- AEA Investors
- Apax Partners
- Ares Management
- Audax Group
- Bain Capital, LLC
- Bain Capital Ventures
- Baird Capital Partners
- Beecken Petty O'Keefe & Company
- The Blackstone Group
- Charterhouse Group, Inc.
- Cressey & Company LP
- Diamond Castle Holdings
- DRI Capital
- DW Healthcare Partners
- Enhanced Equity Fund, L.P.
- Essex Woodlands
- Excellere Partners
- Ferrer Freeman & Company, LLC
- Flexpoint Ford, LLC
- Frazier Healthcare Ventures
- Friedman, Fleischer, and Lowe, LLC
- Frontenac Company
- General Atlantic
- Genstar Capital LLC
- GTCR
- Health Enterprise Partners
- Highlander Partners
- Kohlberg Kravis Roberts & Co.
- KRG Capital
- Linden, LLC
- Madison Dearborn Partners, LLC
- Metalmark Capital
- MTS Health Investors
- Nautic Partners, LLC
- Norwest Equity Partners
- Oak Hill Capital Partners
- One Equity Partners
- Ontario Teachers' Pension Plan (OTPP)
- Persistence Capital Partners
- Psilos
- Riordan, Lewis & Haden Equity Partners
- Riverside Company
- RoundTable Healthcare Partners
- Sterling Partners
- Summer Street Capital Partners
- SV Life Sciences
- TA Associates
- Thomas H. Lee
- TPG Capital
- Vestar Capital Partners
- Waud Capital Partners LLC
- Welsh, Carson, Anderson, & Stowe
