Tacrolimus action pathways in an ointment base for hypertrophic scar prevention in a rabbit ear model

Pharmacotherapy for Keloids and Hypertrophic Scars

Keloids (KD) and hypertrophic scars (HTS), which are quite raised and pigmented and have increased vascularization and cellularity, are formed due to the impaired healing process of cutaneous injuries in some individuals having family history and genetic factors. These scars decrease the quality of life (QOL) of patients greatly, due to the pain, itching, contracture, cosmetic problems, and so on, depending on the location of the scars. Treatment/prevention that will satisfy patients' QOL is still under development. In this article, we review pharmacotherapy for treating KD and HTS, including the prevention of postsurgical recurrence (especially KD). Pharmacotherapy involves monotherapy using a single drug and combination pharmacotherapy using multiple drugs, where drugs are administered orally, topically and/or through intralesional injection. In addition, pharmacotherapy for KD/HTS is sometimes combined with surgical excision and/or with physical therapy such as cryotherapy, laser therapy, radiotherapy including brachytherapy, and silicone gel/sheeting. The results regarding the clinical effectiveness of each mono-pharmacotherapy for KD/HTS are not always consistent but rather scattered among researchers. Multimodal combination pharmacotherapy that targets multiple sites simultaneously is more effective than mono-pharmacotherapy. The literature was searched using PubMed, Google Scholar, and Online search engines.

Treatment of hypopigmented burn hypertrophic scars with short-term topical tacrolimus does not lead to repigmentation

OBJECTIVES

Dyschromia is an understudied aspect of hypertrophic scar (HTS). The use of topical tacrolimus has successfully shown repigmentation in vitiligo patients through promotion of melanogenesis and melanocyte proliferation. It was hypothesized that HTSs treated with topical tacrolimus would have increased repigmentation compared to controls.

METHODOLOGY

Full-thickness burns in red Duroc pigs were either treated with excision and meshed split-thickness skin grafting or excision and no grafting, and these wounds formed hypopigmented HTSs (n = 8). Half of the scars had 0.1% tacrolimus ointment applied to the scar twice a day for 21 days, while controls had no treatment. Further, each scar was bisected with half incurring fractional ablative CO2 laser treatment before topical tacrolimus application to induce laser-assisted drug delivery (LADD). Pigmentation was evaluated using a noninvasive probe to measure melanin index (MI) at Days 0 (pretreatment), 7, 14, and 21. At each timepoint, punch biopsies were obtained and fixed in formalin or were incubated in dispase. The formalin-fixed biopsies were used to evaluate melanin levels by H&E staining. The biopsies incubated in dispase were used to obtain epidermal sheets. The ESs were then flash frozen and RNA was isolated from them and used in quantitative reverse transcription polymerase chain reaction for melanogenesis-related genes: Tyrosinase (TYR), TYR-related protein-1 (TYRP1), and dopachrome tautomerase (DCT). Analysis of variance test with Šídák's multiple comparisons test was used to compare groups.

RESULTS

Over time, within the grafted HTS and the NS group, there were no significant changes in MI, except for Week 3 in the -Tacro group. (+Tacro HTS= pre = 685.1 ± 42.0, w1 = 741.0 ± 54.16, w2 = 750.8 ± 59.0, w3 = 760.9 ± 49.8) (-Tacro HTS= pre = 700.4 ± 54.3, w1 = 722.3 ± 50.7, w2 = 739.6 ± 53.2, w3 = 722.7 ± 50.5). Over time, within the ungrafted HTS and the NS group, there were no significant changes in MI. (+Tacro HTS= pre = 644.9 ± 6.9, w1 = 661.6 ± 3.3, w2 = 650.3 ± 6.2, w3 = 636.3 ± 7.4) (-Tacro HTS= pre = 696.8 ± 8.0, w1 = 695.8 ± 12.3, w2 = 678.9 ± 14.0, w3 = 731.2 ± 50.3). LADD did not lead to any differential change in pigmentation compared to the non-LADD group. There was no evidence of increased melanogenesis within the tissue punch biopsies at any timepoint. There were no changes in TYR, TYRP1, or DCT gene expression after treatment.

CONCLUSION

Hypopigmented HTSs treated with 0.1% tacrolimus ointment with or without LADD did not show significantly increased repigmentation. This study was limited by a shorter treatment interval than what is known to be required in vitiligo patients for repigmentation. The use of noninvasive, topical treatments to promote repigmentation are an appealing strategy to relieve morbidity associated with dyschromic burn scars and requires further investigation.

Microsponge-Based Gel Loaded with Immunosuppressant as a Simple and Valuable Strategy for Psoriasis Therapy: Determination of Pro-Inflammatory Response through Cytokine IL-2 mRNA Expression

Tacrolimus (TL) is a topical calcineurin inhibitor immunosuppressive drug widely used to manage various skin disorders. Herein, we report a TL-loaded microsphere gel formulation with severe atopic dermatitis effects that are required to manage skin disorders. The current study adopted a modified emulsion solvent evaporation technique to synthesize TL-loaded microspheres, which were further converted into gels for skin use. Characterization of the synthesized formulation was performed by differential dynamic light scattering, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray crystallography, Brunauer-Emmett-Teller (BET) analysis, differential scanning calorimetry, and drug release. A Franz diffusion cell was used to study the diffusion of TL for up to 8 h at pH 6.8 and 5.5. Evaluation of cell viability was determined by MTT assay and showed higher IC50 values compared to the plain drug. RNA extraction, real-time polymerase chain reaction (RT-PCR), and reverse transcription were also performed to determine the expression levels of the anti-inflammatory cytokine IL-2. Particle size determination was performed by a zeta sizer, and the TL microsphere size was 1745 ± 70 nm with a good polydispersity (0.337 ± 0.12). The drug entrapment efficiency was also very good at 60% ± 10, and the drug release was 93.9% ± 3.5 within 8 h. An in vitro diffusion study of the formulation also showed improved permeability at both pH values (4.5 and 5.5). The findings of the hemolytic tests demonstrated that TL-MG at concentrations of 50, 100, and 200 mg/mL did not produce any hemolysis. A dose-dependent pattern of cytotoxicity was found during the cell viability assay, with an IC50 value of 787.55 ± 12.78 µg/mL. There was a significant decrease in the IL-2 level in the TL-MG group compared to the other groups. TL-MG microspheres were nontoxic carriers for tacrolimus delivery, with greater loading capacity, a significant release profile, and enhanced cellular uptake with improved permeability.

Advances in Immunomodulatory Mechanisms of Mesenchymal Stem Cells-Derived Exosome on Immune Cells in Scar Formation

Pathological scars are the result of over-repair and excessive tissue proliferation of the skin injury. It may cause serious dysfunction, resulting in psychological and physiological burdens on the patients. Currently, mesenchymal stem cells-derived exosomes (MSC-Exo) displayed a promising therapeutic effect on wound repair and scar attenuation. But the regulatory mechanisms are opinions vary. In view of inflammation has long been proven as the initial factor of wound healing and scarring, and the unique immunomodulation mechanism of MSC-Exo, the utilization of MSC-Exo may be promising therapeutic for pathological scars. However, different immune cells function differently during wound repair and scar formation. The immunoregulatory mechanism of MSC-Exo would differ among different immune cells and molecules. Herein, this review gave a comprehensive summary of MSC-Exo immunomodulating different immune cells in wound healing and scar formation to provide basic theoretical references and therapeutic exploration of inflammatory wound healing and pathological scars.

[Research advances on pharmacological interventions for hypertrophic scar]

Hypertrophic scar is an abnormal fibrous proliferative disease that occurs after deep cutaneous injury, which not only affects aesthetics and function but also has negative psychological effects on the patients. However, the mechanism of hypertrophic scar formation has not been fully elucidated, and its clinical treatment is complex with a high rate of recurrence and no radicle cure. Intervention based on molecular targets will likely be the future direction for the prevention and treatment of hypertrophic scar. In this article, we review the specific roles and mechanisms of drug-targeted interventions in hypertrophic scar formation, including general drugs, cytokines, immunomodulators, herbal extracts, exosomes, and nanomaterials, in the context of advances in both basic and clinical research at home and abroad.

Traditional Chinese medicine for hypertrophic scars—A review of the therapeutic methods and potential effects

Hypertrophic scar (HS) is a typical pathological response during skin injury, which can lead to pain, itching, and contracture in patients and even affect their physical and mental health. The complexity of the wound healing process leads to the formation of HS affected by many factors. Several treatments are available for HS, whereas some have more adverse reactions and can even cause new injuries with exacerbated scarring. Traditional Chinese Medicine (TCM) has a rich source, and most botanical drugs have few side effects, providing new ideas and methods for treating HS. This paper reviews the formation process of HS, the therapeutic strategy for HS, the research progress of TCM with its relevant mechanisms in the treatment of HS, and the related new drug delivery system of TCM, aiming to provide ideas for further research of botanical compounds in the treatment of HS, to promote the discovery of more efficient botanical candidates for the clinical treatment of HS, to accelerate the development of the new drug delivery system and the final clinical application, and at the same time, to promote the research on the anti-HS mechanism of multiherbal preparations (Fufang), to continuously improve the quality control and safety and effectiveness of anti-HS botanical drugs in clinical application.