Strategies for antimicrobial peptide coatings on medical devices: a review and regulatory science perspective.

Indwelling and implanted medical devices are subject to contamination by microbial pathogens during surgery, insertion or injection, and ongoing use, often resulting in severe nosocomial infections. Antimicrobial peptides (AMPs) offer a promising alternative to conventional antibiotics to reduce the incidence of such infections, as they exhibit broad-spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria, microbial biofilms, fungi, and viruses. In this review-perspective, we first provide an overview of the progress made in this field over the past decade with an emphasis on the local release of AMPs from implant surfaces and immobilization strategies for incorporating these agents into a wide range of medical device materials. We then provide a regulatory science perspective addressing the characterization and testing of AMP coatings based on the type of immobilization strategy used with a focus on the US market regulatory niche. Our goal is to help narrow the gulf between academic studies and preclinical testing, as well as to support a future literature base in order to develop the regulatory science of antimicrobial coatings.

Synergistic interplay between the two major bone minerals, hydroxyapatite and whitlockite nanoparticles, for osteogenic differentiation of mesenchymal stem cells.

The inorganic part of human bone is mainly composed of hydroxyapatite (HAP: Ca10(PO4)6(OH)2) and whitlockite (WH: Ca18Mg2(HPO4)2(PO4)12) minerals, where the WH phase occupies up to 20-35% of total weight. These two bone minerals have different crystal structures and physicochemical properties, implying their distinguished role in bone physiology. However, until now, the biological significance of the presence of a certain ratio between HAP and WH in bone is unclear. To address this fundamental question, bone mimetic scaffolds are designed to encapsulate human mesenchymal stem cells (MSCs) for assessing their osteogenic activity depending on different ratios of HAP and WH. Interestingly, cellular growth and osteogenic differentiation are significantly promoted when MSCs are grown with a 3-1 ratio of HAP and WH nanoparticles, which is similar to bone. One of the reasons for this synergism between HAP and WH in hydrogel scaffolds is that, while WH nanoparticles can enhance osteogenic differentiation of MSCs compared to HAP, WH counterintuitively decreases the mechanical stiffness of nanocomposite hydrogels and hinders the osteogenic activity of cells. Taken together, these findings identify the optimal ratio between two major minerals in bone mimetic scaffolds to maximize the osteogenic differentiation of MSCs. STATEMENT OF SIGNIFICANCE: Human bone minerals are composed of HAP and WH inorganic nanoparticles which have different material properties. However, the reason for the coexistence of HAP and WH in human bone is not fully identified, and HAP and WH composite biomaterial has not been utilized in the clinic. In this study, we have developed bone mimetic HAP and WH nanocomposite hydrogel scaffolds with various ratios. Importantly, we found out that HAP can promote the mechanical stiffness of the composite hydrogel scaffolds while WH can enhance the osteogenic activity of stem cells, which together induced synergism to maximize osteogenic differentiation of stem cells when mixed into 3-1 ratio that is similar to human bone.

Perceptions and Practices of the Iranian Population regarding Skin Cancers: A Literature Review.

Despite being preventable, more than 15% of all cancer cases in Iran occur in the skin, making them the most commonly diagnosed malignancy in the country. The purpose of this study is to gain an insight into the current skin cancer related knowledge, attitudes, beliefs, and practices among the Iranian population. A systematic computer based literature search was conducted using databases for articles published through April 2017. Research studies included those that measured skin cancer or sun protection related knowledge, attitudes, beliefs, and behaviors in different Iranian population groups. Exclusion criteria for the articles included (1) irrelevant topics to the review article's aim, (2) articles that focused on the treatment of skin cancers instead of prevention practices, and (3) similar studies conducted on populations not indigenous to Iran. A total of 25 articles that met the eligibility criteria were included in the review. Predominant data were collected via questionnaires. Skin cancer related knowledge varied from low to high across the studies. Moreover, there was a pattern of low perceived skin cancer susceptibility and severity. Overall, there was low usage of sun protection methods among the Iranian population. The findings of this study show that efforts to prevent skin cancer are needed. Education concerning the dangers of sun exposure as well as strategies used to prevent or lower the risk of developing skin cancer should be stressed.