Heprasil is a mixture of thiol-modified hyaluronic acid thiol-modified heparin. Heprasil is a component of the HyStem-HP kits, but can be purchased separately here. Comes with 10 mL of Buffer A. HyStem V2.0 kit components are reconstituted with a buffered 1X PBS. The resulting components will also result in a pH neutral isotonic salt hydrogel. The ending pH, osmo, and rheological properties are the same from Version 1.0 to Version 2.0. Heprasil is thiol-modified hyaluronic acid with thiol-modfied heparin and is a component of the HyStem hydrogel kit. Hyaluronic acid is a major constituent of native extracellular matrix (ECM). Heparin is also present in the ECM as heparan sulfate. Most cells do not attach to Heprasil-only hydrogels. Heprasil must be used in conjunction with Gelin-S or ECM proteins such as laminin, collagen, or fibronectin for most 3-D cell culture and tissue-engineering applications.