The soluble form of Ac-SDKP peptide, derived from thymosin beta-4, has been described as a natural inhibitor of pluripotent hematopoietic stem cell proliferation and as a stimulator of angiogenesis, both in vitro and in vivo (Koutrafouri et al., 2001; Wang et al., 2004). This peptide has been selectively bound to acrylated hyaluronic acid hydrogels via thiol groups from cysteine residues (Song et al., 2014). Unfortunately, the immobilization process was poorly characterized and the effect of hydrogels on EC function was not tested in vitro. In a mouse model of chronic myocardial infarction, hydrogels with immobilized Ac-SDKP did not show improved regeneration potential. Yet, Ac-SDKP-HA hydrogels with entrapped stem cell homing factor SDF-1 showed a significant increase of myocardial regeneration and recovery of heart function, as compared to groups with only one or none of these factors, suggesting a potentially interesting synergistic effect.
5-HTP is sometimes taken by people coming down from MDMA to relieve post-MDMA dysphoria.[8] As 5-HTP is a necessary precursor for the brain to produce more serotonin, and MDMA use depletes a person's natural serotonin levels, it is believed that taking 5-HTP after consuming MDMA will speed up serotonin production. DanceSafe claims that the anecdotal evidence is widespread and that the theory is physiologically reasonable.[9] Backing up this approach is research conducted by Wang, et al.  in 2007, which observed that MDMA-induced depletions of 5-HT (serotonin) were restored in rats after administration 5-HTP, and suggested that this approach might be clinically useful in abstinent MDMA users.[8]