From Root to Ritual
Daily science, ritual, and botanical intelligence for hair and scalp health. By Laritelle Organic.
From Root to Ritual
PRP just got its most rigorous review yet. 43 randomised controlled trials, 1,877 patients. Here is what the evidence actually says.
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Platelet-rich plasma therapy has been used in hair restoration for over a decade. The clinical evidence has been accumulating and has now reached a scale that allows a definitive summary. A comprehensive meta-analysis published in 2025, covering a search of PubMed, Mbasi, and Scopus through July 2025, identified 43 randomized controlled trials with 1,877 participants assessing PRP in alopecia. The headline finding is unambiguous. Activated PRP was effective in increasing hair density and minimizing recurrence compared with placebo, whereas non-activated PRP was associated with a higher frequency of adverse effects. Separate 2026 clinical data tracking outcomes in over 2,800 patients across multiple treatment centers confirmed an average increase of 45.9 hairs per square centimeter after three initial treatments, with improvements continuing for up to 12 months, and maintained through follow-up sessions. The nuance most people seeking PRP treatment never encounter, and that most clinic marketing never highlights, is in those two words, activated versus non-activated. Whether the PRP is activated before injection is the variable that most determines whether growth factors are actually released at the treatment site, and the 2025 meta-analysis confirms it also determines the safety profile. What PRP is the mechanism, and why activation changes everything. PRP is prepared from the patient's own blood, autologous, meaning no donor material, no rejection risk. The blood is centrifuged to separate its components, red blood cells, white blood cells, plasma, and platelets. The platelet-rich fraction is then concentrated to five, ten times the normal platelet count found in regular blood, creating a preparation that carries a proportionally concentrated load of the growth factors platelets naturally release during tissue repair. Those growth factors, platelet-derived growth factor, PDGF, vascular endothelial growth factor, VEGF, transforming growth factor beta, TGFB, insulin-like growth factor, IGF 1, and epidermal growth factor, EGF, are the same signaling molecules that this series has covered across multiple articles. VEGF is what ginger's 6 gingerole upregulates and what exosomes deliver. IgF1 is what rosemary upregulates and what growth hormone releases during deep sleep. TGFB in its repair role is what exosome cargo includes. PRP is delivering all of these simultaneously from the patient's own concentrated platelet supply directly into the parapolicular tissue. Activated versus non-activated. The critical distinction platelets are inactive until they encounter an activating signal, normally the collagen exposed at a wound site, or biochemical activators like thrombin. In their resting state, the growth factor cargo is stored inside the platelet's alpha granules and not released. Activated PRP. The platelet preparation is treated with an activating agent, calcium chloride or thrombin, before injection. This triggers degranulation. The platelets really ace their alpha granule contents at the point of preparation, meaning the growth factors are immediately available in the injectable solution and at the injection site. Non-activated PRP. The platelets are injected in their resting state, with the assumption that the trauma of the injection itself will trigger activation. The 2025 meta-analysis found this approach is associated with a higher frequency of adverse effects, suggesting that unpredictable, potentially excessive activation from injection trauma, rather than controlled pre-injection activation, produces a less favorable response. When seeking PRP treatment, ask specifically whether the preparation is activated before injection and what activating agent is used. This single question identifies whether the clinic is following the protocol that the 43 RCT meta-analysis found effective. 43 RCTs 1,877 participants, the largest meta-analysis of PRP for alopecia to date, published 2025, covering studies from 2000 to 2025, 45.9. Average hairs per square centimeter increase after three initial treatments in 2026 clinical dataset of 2,800-plus patients, with improvements continuing for up to 12 months, 70-80% success rate in early to moderate stage hair loss, with best outcomes when treatment begins within the first year of noticeable thinning. The mechanisms in context. VEGF, angiogenesis and the oxygen supply. VEGF triggers new blood vessel formation around the follicle. The same mechanism that ginger's 6 gingerole drives botanically, that LLLT drives through photobiomodulation, and that exosomes deliver through growth factor cargo. PRP delivers VEGF in concentrated form directly into the parapollicular tissue at the point where goleal tension and follicular ischymia are creating the low oxygen environment that HIF1A is signaling. PRP may improve hair density and thickness and reduce shedding-related measures in selected patients, and the VGF-driven angiogenic response is a primary mechanism through which it does so. IgF-1, dermal papilla activation, IgF-1, insulin-like growth factor 1, is the primary systemic signal that activates follicle stem cells and drives antigen initiation. Growth hormone released during deep sleep delivers it systemically. Rosemary upregulates its local expression in dermal papilla cells. PRP delivers it directly in concentrated form to the dermal papilla. This is the gas 6 signaling story from a different angle. IgF1 and gas 6 both feed into the antigen activation cascade from the dermal papilla to the follicle stem cells. PRP delivers both directly, bypassing the cortisol suppression mechanism that blocks gas 6 and the deep sleep requirement that limits growth hormone delivery. Anti inflammatory modulation The PILIF environment in PRP's platelet release profile operates in its tissue repair role. Modulating the inflammatory environment rather than driving the fibrotic response that chronic TG