But they are chemically different things that do different jobs
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Caplan offers an important caveat: results in small clinical trials and results in the general population are often very different

related full-length recombinant thymosin beta-4 (a different formulation than the marketed TB-500 fragment) has also been examined in small human studies for cardiac and dermatologic indications Examined in preclinical models, including diabetic rat Achilles tendon and rat ligament-injury studies, for actin-binding, cell-migration, and angiogenic activity that researchers have proposed as a mechanism for tendon and ligament repair, though this literature remains comparatively sparse for musculoskeletal applications specifically Known risks and side effects: Because TB-500 is manufactured and sold without FDA oversight as a "research chemical," independent testing and industry reporting describe wide variability in purity (with some products measured well below labeled potency) and contamination with heavy metals or bacterial byproducts, unlike pharmaceutical-grade recombinant thymosin beta-4 used in registered clinical trials Thymosin beta-4's core mechanisms, angiogenesis and cell migration, are also pathways exploited by tumors

What GHK-Cu Treats: Facial Aging: Fine lines, wrinkles, and loss of skin firmness Skin Texture Issues: Rough texture, enlarged pores, and uneven skin tone Sun Damage: Age spots, hyperpigmentation, and photoaging Hair Loss: Thinning hair, pattern baldness, and poor hair quality Scarring: Acne scars, surgical scars, and wound healing Skin Thinning: Age-related skin thinning and fragility Mechanism of Action: GHK-Cu works by binding copper ions to create a bioactive complex that penetrates deep into skin tissues
Reconstituted formulas must be kept in a dark refrigerator at 28C and are typically best used within 4 to 8 weeks