The CEL™ Complex helps skin regulate itself, then renew.
The CEL™ Complex is a patent-pending blend of plant-derived exosomes, peptides and botanical extracts, developed in our French epigenetic laboratory. It is in CEL™ Retinal Serum, CEL™ Eye Cream and CEL™ Reset Serum.
Healthy skin runs its own triage. It keeps the cells that work and clears the ones that do not. That system slows with age. The CEL™ Complex is formulated to help it work again, without overriding the skin's biology.
CEL™ Complex was a finalist in the IMCAS 2026 Industry Innovation Awards. IMCAS is one of the largest congresses on ageing science.
What happened when we tested it on real human skin.
Ex vivo. Independent anatomical pathology laboratory. Healthy, undamaged tissue. No UV stress. No induced damage of any kind.
Most skincare efficacy testing stops at the petri dish - isolated cells, treated with a single ingredient, measured in a culture medium. We commissioned an independent anatomical pathology laboratory to test the CEL™ complex on intact human skin tissue, epidermis and dermis together, under a microscope. The skin was healthy throughout. Its response was spontaneous.
After 56 days, skin measured 8% firmer and 10% more elastic. Around the eyes, 9% firmer and 18% more elastic.
CEL™ Retinal Serum is a face serum that pairs CEL™ Complex with encapsulated retinal. Women aged 35 to 60, all with sensitive skin, used it for eight weeks. At four weeks, 95% of them reported firmer-looking skin, and by eight weeks every participant did. Wrinkle depth measured 12% lower over the same period.
CEL™ Eye Cream brings CEL™ Complex to the eye area. Women aged 40 to 65 used it for eight weeks. Every participant reported a firmer-looking eye area, with dark circles and puffiness visibly reduced.
The lab study below looks at what happens deeper in the skin.
Firmness, elasticity and wrinkle depth measured on 11 women per study, before and after 56 days, with statistically significant results. Questionnaire results as reported by 20 and 22 participants.
Tested on human skin, in the lab
Within hours, more of the cells that make collagen were at work.
Collagen's building block is called procollagen I. Cells deep in the skin make it before it is assembled into collagen fibers. Researchers use it as a marker of new collagen being made.
Aged skin makes less. In two peer-reviewed studies, people over 80 had 52% and 68% less type I procollagen than people aged 18 to 29.
CEL™ Reset Serum, the finished product of CEL™ Complex, was applied once to the surface of intact, healthy human skin from a donor. At 4.5 hours, the dermis had 34.76% more cells making procollagen I than untreated skin at the start. The dermis is the deeper layer of the skin, where collagen is made.
Method: exploratory ex vivo study on fresh skin from one healthy donor, with no UV exposure and no induced damage. Procollagen I-positive cells counted by immunofluorescence at five time points over 4.5 hours, read by an anatomical pathologist. Compared with untreated skin at the start.
Tested on healthy skin, like yours.
When skin is damaged, it sets off its own recovery. Part of that recovery is making new collagen. This happens with or without a product.
The skin in this study had no UV exposure and no damage induced first. It had nothing to recover from. The rise measured at 4.5 hours followed one application of CEL™ Reset Serum. On healthy skin.
The study was conducted on CEL™ Reset Serum, a professional treatment available through medical dispensing. CEL™ Reset Serum is the finished product of CEL™ Complex.
Tested free of estrogenic and androgenic endocrine disruption.
Every Skin Diligent finished formula is tested this way.
FAQ
What exactly is in the CEL™ complex and what makes it different?
CEL stands for Cellular Epigenetic Longevity. A patent-pending bioactive blend of plant-derived exosomes, peptides, and botanical extracts, developed in our French epigenetic laboratory. Formulated to work in calibrated cycles, supporting the skin's natural renewal processes through intermittent, dose-dependent action.
Which products contain CEL™?
CEL™ Retinal Serum, CEL™ Eye Cream and CEL™ Reset Serum. CEL™ Reset Serum is a professional treatment, available through medical dispensing.
What results can I expect, and when?
With CEL™ Retinal Serum, 95% of participants reported firmer-looking skin at four weeks, and all of them at eight weeks. After 56 days, skin measured 8% firmer and 10% more elastic, and wrinkles measured 12% shallower. Around the eyes, skin measured 18% more elastic and 9% firmer after 56 days of CEL™ Eye Cream.
What does longevity skincare actually mean - and how is it different from anti-aging?
Longevity skincare focuses on supporting the skin's own maintenance over time - not correcting surface signs after they appear, but creating the conditions for skin to stay healthier for longer. At Skin Diligent, this means working at the level of how skin cells read and act on their own instructions.
How do I know the science is real and not just marketing?
CEL™ Reset Serum, the finished product of CEL™ Complex, was tested ex vivo on intact, healthy human skin and read by an anatomical pathologist. CEL™ Retinal Serum and CEL™ Eye Cream were each tested on women for 56 days, with instrumental measurements and questionnaires.
What happened to the skin in the study?
At 4.5 hours after one application, the dermis had 34.76% more cells making procollagen I, the building block of collagen, than untreated skin at the start. Under the microscope, the tissue showed no visible damage. The study was exploratory, on skin from one healthy donor.
Why test the finished formula?
Your skin meets the whole formula. Every finished formula is tested free of estrogenic and androgenic endocrine disruption. CEL™ Reset Serum was also tested as a finished product on intact human skin.
Sources
Varani J, June 2006, American Journal Of Pathology 168(6):1861-8. Fisher GJ, Datta SC, Talwar HS, et al. Molecular basis of sun-induced premature skin ageing and retinoid antagonism. Nature. 1996;379(6563):335-339. Quan T, Qin Z, Xia W, Shao Y, Voorhees JJ, Fisher GJ. Matrix-degrading metalloproteinases in photoaging. Journal of Investigative Dermatology Symposium Proceedings. 2009;14(1):20-24. Varani J, Dame MK, Rittie L, et al. Inhibition of type I procollagen synthesis by damaged collagen in photoaged skin and by collagenase-degraded collagen in vitro. American Journal of Pathology. 2006;168(6):1861-1868. Lichtman MK, Otero-Vinas M, Falanga V. Transforming growth factor beta (TGF-beta) isoforms in wound healing and fibrosis. Wound Repair and Regeneration. 2016;24(2):215-222. Finnson KW, McLean S, Di Guglielmo GM, Philip A. Dynamics of transforming growth factor beta signaling in wound healing and scarring. Advances in Wound Care. 2013;2(5):195-214.