This present disclosure relates to a method of producing a proteoglycan having anticoagulant activity, comprising of and providing a cell transfected with a recombinant nucleic acid encoding a core protein having one or more glycosaminoglycan attachment sites； and incubating the cell under conditions to promote the production of a proteoglycan comprising the core protein linked to heparin and/or HS and optionally other glycosaminoglycan chains, and to heparin or heparan sulphate isolated from such proteoglycans that have significant anti- coagulant activity. The invention also relates to a recombinant proteoglycan comprising a core protein and heparin and/or heparan sulfate, to a cell capable of producing a proteoglycan comprising the core protein and heparin and/or heparan sulfate, and to a method of treating or preventing blood coagulation, or a condition associated with blood coagulation, using the recombinant proteoglycan comprising a core protein and heparin and/or heparan sulfate and/or the heparin and/or heparan sulfate isolated from such proteoglycans.
