The aim of this study is to evaluate the clinical, cellular, and molecular effects of Royalactin as an adjunct to standard treatment, compared to standard treatment alone, in the treatment of Wagner grade II diabetic foot ulcers by assessing wound size, cell behavior (Epithelialization, polymorphonuclear neutrophils, fibroblasts, angiogenesis, and collagen), and growth factor expression. This is a prospective, randomized, double-blind, double-blind, experimental, longitudinal, comparative, controlled clinical trial.

Materials and methods

Ethical Considerations The study was conducted in compliance with Good Clinical Practice (GCP) guidelines. All procedures adhered to the ethical standards of the Research and Bioethics Committee of the XXXXXXXXXX. the Declaration of Helsinki, and the General Health Law. Protocols were strictly followed, data were handled with rigorous confidentiality, and informed consent was obtained from all participants.

Inclusion Criteria Adult patients with Diabetes Mellitus undergoing treatment for foot and ankle wounds were included. Eligibility criteria required wounds larger than 4 cm², with more than 80% granulation tissue, involving skin, fat, or ligaments without bone involvement, and non-infected (Wagner Grade II). Additional requirements included a duration of more than 2 months, an ankle-brachial index (ABI) greater than 0.5, the signing of the informed consent form, and the ability to attend dressing changes three times per week for 4 weeks.

Experimental Agents and Randomization The FEMSA Biotechnology Center laboratory produced 20 tubes (50 ml) containing gold nanoparticles and emulsifiers. Ten tubes were formulated with Royalactin at 0.2 g/L, while the other 10 served as the control without the peptide. The laboratory randomized, numbered, and paired the tubes, providing a list for paired application.

Treatment Protocol Standardized dressing changes were performed three times per week for 4 weeks at the Chronic Wound, Diabetic Foot, and Hyperbaric Medicine Center of XXXXX. Each wound was first irrigated with sterile water and dried with sterile gauze. The wound was then divided (or the division was remarked) using black ink on the skin, and a 0.5 cm strip of Hypafix (BSN medical GmbH, ESSITY) was applied. A circular label was placed on the perilesional skin to identify the tube number (bottom), patient ID (top-right), and dressing change number (top-left).

Standard photographs were taken (Camera+ App, iPhone 15 Pro Max). The area was gently debrided three times with sterile gauze moistened with 0.12% Chlorhexidine (Clorhexi-Clean®, PISA). Ketanserin 2% gel (Sufrexal®, Janssen) was applied to both sides, followed by the application of the corresponding gel (Royalactin or placebo) to each designated wound section. Finally, a primary dressing of sodium carboxymethylcellulose hydrofiber and regenerated cellulose fiber (Aquacell extra®, Convatec) was applied, protected by a secondary adhesive border gauze dressing (Border gauze®, Medline).

Data Collection and Histological Analysis During the first and last dressing changes (sessions 1 and 13), photographs were taken to measure the area of each side in cm² (IMITO measure App, iPhone 15 Pro Max). Additionally, 3 mm punch biopsies of the granulation tissue were obtained from the distal edge of each side.

Biopsy samples were sectioned, labeled, and stained using Hematoxylin and Eosin (H&E), Masson's Trichrome, and immunohistochemistry (IHC) for the expression of:

• CD31 (Roche)
• Vascular Endothelial Growth Factor (VEGF) (Biocare)
• Epidermal Growth Factor Receptor (EGFR) (Cell Marque).

Statistical Analysis and Evaluation Results from sessions 1 and 13 were evaluated. Wound size was recorded in cm². Epithelialization, polymorphonuclear neutrophils (PMN), fibroblasts, angiogenesis, and collagen were scored according to a semi-quantitative histological scale for wound assessment. The percentage of tissue expressing VEGF and EGFR, as well as the intensity of expression (scored 0 to 3+), were reported separately (Figure 1 G-I). Data were compared at baseline and at four weeks, both as a total cohort and by comparing the Control vs. Royalactin groups; individual variables were also analyzed.

Inclusion Criteria:

- Confirmed diagnosis of Diabetes Mellitus according to the 2020 ADA guidelines.

• Stage II ulcer according to the Wagner classification for Diabetic Foot (deep ulcer, penetrating ligaments and muscles, without bone involvement or abscess formation).
• Ulcer located on any area of the foot or ankle.
• Ulcer with 80% granulation tissue.
• Ankle-brachial index greater than 0.5 (not considered severe or critical arterial disease).
• Negative stylet test.
• Ability to attend wound care and follow-up appointments three times a week for four weeks.
• Signed informed consent form.

Exclusion Criteria:

- History of hypersensitivity reactions to dermatological products.

• History of generalized dermatological pathology or pathology affecting the foot.
• Diagnosis of autoimmune disease.
• Local or systemic infection.
• Hypersensitivity to any of the components of the experimental product.

The informed consent form signed by the patients specifies that their personal data will not be shared.