The purpose of this study was to develop a non-invasive method to measure mRNA levels using tape stripping on the skin of patients with psoriasis and patients with atopic dermatitis.

Three sequential groups of subjects were recruited in this study for: 1) skin squame collection; 2) tape strip collection; and 3) tape strip and skin biopsy collection in the aim of identifying the most optimal method for measuring the mRNA levels of skin biomarkers in tape strip samples.

Inclusion Criteria:

• Subject, male or female, aged 18 years or older at the time of consent.

• Female subjects of childbearing potential had a negative urine pregnancy test at the screening visit.

• Subjects had to be able and willing to provide written informed consent and comply with the requirements of the study protocol. Consent was obtained prior to any study-related procedures.

  *Special inclusion criteria for volunteers with atopic dermatitis or psoriasis:

• Patient had a history of atopic dermatitis or psoriasis.

• Patient with psoriasis had a Physician's Global Assessment (PGA) score of ≥2 at Day 0.

• Patients with atopic dermatitis had an Investigator's Global Assessment (IGA) score of ≥2 at Day 0.

Exclusion Criteria:

• Female subject was pregnant or breastfeeding.

• Subject was participating in a clinical trial with an experimental drug or device or had participated in a clinical trial with an experimental drug or device within the last 4 weeks of the collection day (Day 0).

• Subject was known to have hepatitis B or hepatitis C viral infection.

• Subject was known to have immune deficiency or was immunocompromised.

• Subject had used systemic medication, medical devices, UVB or PUVA therapy or natural health products to treat atopic dermatitis or psoriasis on the areas to be biopsied or tape stripped within 4 weeks of the collection day (Day 0).

• Subject had used oral, intravenous steroids, or immunosuppressive medication within 4 weeks of the collection day (Day 0). Subject had used intramuscular or intra-lesional or intra-articular steroids or immunosuppressive medication on the areas to be biopsied or tape stripped within 4 weeks of the collection day (Day 0).

• Subject had used a biologic within 12 weeks or 5 half-lives of the collection day (Day 0), whichever was longer.

• Subject had used topical medication, natural health products or medical devices to treat atopic dermatitis or psoriasis on the areas to be tape stripped or biopsied within 2 weeks of the collection day (Day 0).

  *Only for subjects who underwent skin biopsy:

• Subject had a known hypersensitivity/allergy to lidocaine.

• Subject had a history of hypertrophic scarring or keloid formation in scars or suture sites.

• Subject was taking anti-coagulant medication (e.g. heparin, low molecular weight [LMW]-heparin, warfarin, anti-platelets [nonsteroidal anti-inflammatory drugs (NSAIDs) and low-dose aspirin (equal or lower than 81 mg) were not considered anti-platelets]) or had a contraindication to skin biopsies.