Ac-SDKP vs PEG-MGF

Inhibits hematopoietic stem cell entry into S-phase. Blocks TGF-β1-mediated fibroblast activation, reducing collagen deposition. Promotes angiogenesis via VEGF upregulation. Regulated in vivo by ACE enzyme.

Ac-SDKP (N-acetyl-seryl-aspartyl-lysyl-proline) is an endogenous tetrapeptide generated from the N-terminus of thymosin beta-4 by the enzyme prolyl oligopeptidase, with further regulation by angiotensin-converting enzyme (ACE), and is characterized by roles in hematopoietic progenitor regulation and anti-fibrotic signaling in renal, cardiac, and vascular tissue. Ac-SDKP inhibits collagen synthesis and fibroblast proliferation, reduces TGF-beta-1-mediated fibrotic signaling, and promotes anti-inflammatory macrophage polarization in preclinical models, suggesting a role in tissue homeostasis downstream of the thymosin beta-4 pathway. Preclinical studies in rodent models of renal fibrosis and systemic lupus erythematosus — predominantly from the NIH-funded Rhaleb and Carretero laboratory at Henry Ford Health — have demonstrated that exogenous Ac-SDKP reduces collagen deposition and inflammatory infiltrate; no human clinical trials have been completed or indexed in PubMed. Ac-SDKP has no FDA approval and no approved indication in any jurisdiction; it is studied as a research compound with a plausible anti-fibrotic mechanism and consistent preclinical evidence, but extrapolation of rodent findings to human therapeutic outcomes has not been validated by any clinical investigation.

Pegylated form of MGF; activates muscle stem cells (satellite cells) to repair and regenerate muscle tissue after damage

PEG-MGF (pegylated mechano growth factor) is a synthetic derivative of mechano growth factor (MGF, IGF-1Ec), in which the bioactive C-terminal E-peptide domain of the IGF-1 gene splice variant is chemically conjugated with polyethylene glycol (PEG) to improve aqueous stability and extend its proposed in vivo half-life relative to the rapidly degraded unmodified peptide. PEGylation is intended to preserve the proposed satellite cell-activating and tissue repair-promoting actions of the native MGF E-peptide over a longer post-administration window, with the pharmacological rationale extrapolated from preclinical and in vitro research on the parent MGF compound. No indexed peer-reviewed literature has been identified for PEG-MGF as a distinct chemical entity under its common name or under pegylated IGF-1 splice variant terminology in the biomedical literature, and the compound does not appear in PubMed with characterized pharmacokinetic or pharmacodynamic properties. PEG-MGF has no regulatory approval in any jurisdiction and no published human pharmacokinetic, safety, or efficacy data; it is sold as a research chemical by vendors without an evidence base establishing its biological activity as a defined and characterized therapeutic agent.