Recent advances in gelatin-based therapeutics

Introduction: Biomaterials have provided a wide range of exciting opportunities in tissue engineering and regenerative medicine. Gelatin, a collagen-derived natural biopolymer, has been extensively used in regenerative medicine applications over the years, due to its cell-responsive properties and the capacity to deliver a wide range of biomolecules.

Areas covered: The most relevant properties of gelatin as biomaterial are presented together with its main therapeutic applications. The latter includes drug delivery systems, tissue engineering approaches, potential uses as ink for 3D/4D Bioprinting, and its relevance in organ-on-a-chip platforms.

Expert opinion: Advances in polymer chemistry, mechanobiology, imaging technologies, and 3D biofabrication techniques have expanded the application of gelatin in multiple biomedical research applications ranging from bone and cartilage tissue engineering, to wound healing and anti-cancer therapy. Here, we highlight the latest advances in gelatin-based approaches within the fields of biomaterial-based drug delivery and tissue engineering together with some of the most relevant challenges and limitations.     

Recent advances in targeted delivery of non-coding RNA-based therapeutics for atherosclerosis

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Efficacy of oral colon-specific delivery capsule of low-molecular-weight heparin on ulcerative colitis

Low-molecular-weight heparin has the potential for the treatment of ulcerative colitis, and targeted drug delivery to the colon is important for topical treatment of this disease, so low-molecular-weight heparin oral colon-specific delivery capsule was prepared, and the in vitro and in vivo drug release behavior was investigated. The macroscopical and histological scoring systems, wet colon mass index and myeloperoxidase activity were assessed to evaluate the efficacy of the capsule after administered orally to experimental colitis mice. Serum levels, including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and a link factor of blood coagulation and inflammation factor Xa (FXa) were assayed by enzyme-linked immunosorbent assay. The expression of Musashi-1 (as an intestinal stem cell marker) in the colons was assessed by immunohistochemical analysis. The in vitro and in vivo drug release studies clearly indicated that the specific coated capsules were capable of protecting low-molecular-weight heparin from releasing in stomach and small intestine, while specifically delivering at colon. The oral colon-specific delivery capsule of low-molecular-weight heparin could attenuate macroscopic and histological features of colitis. The results showed that low-molecular-weight heparin oral colon-specific delivery capsule significantly decreased the serum levels of TNF-α, IL-6 as well as FXa, while increased the expression of Musashi-1 in colon compared with acetic acid-induced ulcerative colitis model group. The results showed that low-molecular-weight heparin oral colon-specific delivery capsule had the potential for treatment of inflammatory bowel disease.     

Clinical outcomes with unfractionated heparin or low-molecular-weight heparin as bridging therapy in patients on long-term oral anticoagulants: the REGIMEN registry.

BACKGROUND: Patients who receive long-term oral anticoagulant (OAC) therapy often require interruption of OAC for an elective surgical or an invasive procedure. Heparin bridging therapy has been used in these situations, although the optimal method has not been established. No large prospective studies have compared unfractionated heparin (UFH) with low-molecular-weight heparin (LMWH) for the perioperative management of patients at risk of thromboembolism requiring temporary interruption of long-term OAC therapy. PATIENTS/METHODS: This multicenter, observational, prospective registry conducted in North America enrolled 901 eligible patients on long-term OAC who required heparin bridging therapy for an elective surgical or invasive procedure. Practice patterns and clinical outcomes were compared between patients who received either UFH alone (n = 180) or LMWH alone (n = 721). RESULTS: Overall, the majority of patients (74.5%) requiring heparin bridging therapy had arterial indications for OAC. LMWH, in mostly twice-daily treatment doses, represented approximately 80% of the study population. LMWH-bridged patients had significantly fewer arterial indications for OAC, a lower mean Charlson comorbidity score, and were less likely to undergo major or cardiothoracic surgery, receive intraprocedural anticoagulants or thrombolytics, or receive general anesthesia than UFH-bridged patients (all P < 0.05). The LMWH group had significantly more bridging therapy completed in an outpatient setting or with a < 24-h hospital stay vs. the UFH group (63.6% vs. 6.1%, P < 0.001). In the LMWH and UFH groups, similar rates of overall adverse events (16.2% vs. 17.1%, respectively, P = 0.81), major composite adverse events (arterial/venous thromboembolism, major bleed, and death; 4.2% vs. 7.9%, respectively, P = 0.07) and major bleeds (3.3% vs. 5.5%, respectively, P = 0.25) were observed. The thromboembolic event rates were 2.4% for UFH and 0.9% for LMWH. Logistic regression analysis revealed that for postoperative heparin use a Charlson comorbidity score > 1 was an independent predictor of a major bleed and that vascular, general, and major surgery were associated with non-significant trends towards an increased risk of major bleed. CONCLUSIONS: Treatment-dose LMWH, mostly in the outpatient setting, is used substantially more often than UFH as bridging therapy in patients with predominately arterial indications for OAC. Overall adverse events, including thromboembolism and bleeding, are similar for patients treated with LMWH or UFH. Postoperative heparin bridging should be used with caution in patients with multiple comorbidities and those undergoing vascular, general, and major surgery. These findings need to be confirmed using large randomized trials for specific patient groups undergoing specific procedures.     

Bioavailability of oral carisoprodol 250 and 350 mg and metabolism to meprobamate: A single-dose crossover study

Background: Carisoprodol is a skeletal muscle relaxant indicated for use in the treatment of acute, painful musculoskeletal conditions. Two randomized, controlled clinical trials have reported that carisoprodol 250 mg QID was equally effective as and better tolerated than carisoprodol 350 mg QID.Objectives: The primary objective of the current study was to determine the relative bioavailability of carisoprodol and its metabolite, meprobamate, with singledose administration of 250- and 350-mg tablets. A secondary objective of the study was to determine whether lowering the carisoprodol dose would decrease plasma meprobamate concentrations.Methods: This single-dose, randomized, open-label, crossover study enrolled healthy volunteers. Each dose was administered with water in the morning; after a 7-day washout, subjects received the alternate dose. Blood samples were drawn at prespecified times over a 48-hour period. For tolerability assessment, subjects underwent a physical examination, including 12-lead ECG.Results: A total of 24 subjects were enrolled (12 men, 12 women; mean age, 22.8 years). The dose-adjusted AUC_0−∞ values for carisoprodol were 5.29 μg/mL/h with the 250-mg tablet and 5.75 μg/mL/h with the 350-mg tablet (relative bioavailability, 92%). The mean (SD) C_max values of carisoprodol and meprobamate after administration of the 250-mg carisoprodol tablet were 1.24 (0.49) and 1.84 (0.31) μg/mL, respectively, compared with 1.78 (0.97) and 2.46 (0.47) μg/mL with the 350-mg tablet. AUC_0−∞ was dose proportional, and the apparent t_1/2 values at the terminal phase were 1.74 hours with the 250-mg tablet and 1.96 hours with the 350-mg tablet. There were 3 mild adverse events considered possibly treatment related (weakness, dizziness, and drowsiness); these were reported in 2 subjects with 350-mg carisoprodol.Conclusions: In this small study in healthy fasting subjects, the exposure to carisoprodol and meprobamate was dose proportional between the single 250- and 350-mg doses. Both doses were generally well tolerated.     

Patients requiring interruption of long-term oral anticoagulant therapy: the use of fixed sub-therapeutic doses of low-molecular-weight heparin

Summary.  Introduction:  We tested the efficacy and safety of fixed doses of low-molecular-weight heparin (LMWH) in patients requiring interruption of vitamin-K antagonist (VKA) because of invasive procedures. Methodology:  Preoperatively, patients discontinued VKA for 5 ± 1 days; in those at low risk for thrombosis, LMWH was given at a prophylactic dosage of 3800 UI (nadroparin) or 4000 UI (enoxaparin) anti-factor (F) Xa once daily the night before the procedure. In patients at high risk for thrombosis, LMWH was started early after VKA cessation and given at fixed sub-therapeutic doses (3800 or 4000 UI anti-FXa twice daily) until surgery. Postoperatively, LMWH was reinitiated 12 h after procedure while VKA was reinitiated the day after. Heparin was continued until a therapeutic INR value was reached. The primary efficacy endpoints were the incidence of thromboembolism and major bleeding from VKA suspension (because of surgery) up to 30 ± 2 days postprocedure. Results:  A total of 328 patients (55.4% at low risk and 44.6% at high risk for thrombosis) were enrolled; 103 (31.4%) underwent major surgery and 225 (68.6%) non-major invasive procedures. Overall, thromboembolic events occurred in six patients (1.8%, 95% confidence interval 0.4–3.2), five belonging to the high-risk group and one belonging to the low-risk group. Overall, major bleeding occurred in seven patients (2.1%, 95 confidence interval 0.6–3.6), six patients belonged to the high-risk group and one belonged to the low-risk group; most of the events occurred in the high-risk group during major surgery. Conclusion:  LMWH given at fixed sub-therapeutic doses appears to be a feasible and safe approach for bridging therapy in chronic anticoagulated patients.     

Lipidic prodrug approach for improved oral drug delivery and therapy

In the past, a prodrug design was used as a last option to improve bioavailability through controlling transport, distribution, metabolism, or other mechanisms. Prodrugs are currently used even in early stages of drug development, and a significant percentage of all drugs in the market are prodrugs. The focus of this article is lipidic prodrugs, a strategy whereby a lipid carrier is covalently bound to the drug moiety. The increased lipophilicity of the lipid-drug conjugate can improve the pharmacokinetic profile and provide meaningful advantages: increased absorption across biological barriers, prolonged circulation half-life, selective distribution profile (eg brain penetration), reduced hepatic first-pass metabolism, and overall enhanced bioavailability of the parent drug. Moreover, lipidic prodrugs may join the endogenous lipid trafficking pathways, thereby facilitate drug targeting, either by selective absorption pathway (eg lymphatic transport) or drug release at specific target site(s). The different lipid-drug conjugates (triglyceride-, fatty acids, phospholipid-, and steroid-based prodrugs), the physiological barriers that challenge the absorption of these conjugates, followed by their current utilization and potential clinical benefits are described and analyzed, and future opportunities this approach could provide are discussed. Altogether, lipidic prodrugs represent an exciting approach for improving different aspects of oral drug delivery/therapy and may provide solutions for various unmet needs; the use of this strategy is expected to grow.     

Low-molecular-weight heparin for the long-term treatment of symptomatic venous thromboembolism: meta-analysis of the randomized comparisons with oral anticoagulants

Summary. Background: The management of venous thromboembolism (VTE) requires an initial treatment with unfractionated heparin (UFH) or low‐molecular‐weight heparin (LMWH), followed by oral anticoagulants (OA) for at least 3 months. OA treatment however, requires laboratory monitoring of anticoagulation, carries a definite risk of bleeding, and may be contraindicated in some patients. As an alternative to vitamin K antagonists, subcutaneous LMWH has been proposed and evaluated in randomized clinical trials, but they are all small studies that lack the power to establish if these two treatment modalities are equivalent in efficacy or safety. Objectives: The objective of this review was to evaluate the efficacy (VTE recurrence) and safety (bleeds and deaths) of long‐term treatment of VTE with LMWH compared with OA. A secondary endpoint was to evaluate the effect of LMWH on cancer mortality. Methods: Computerized searches of MedLine and EmBase were performed. In addition, randomized clinical trials were located through personal communication with colleagues, and through the manual scanning of meeting proceedings and reference lists of relevant studies. When necessary, the authors of the selected papers were called to obtain additional information. Two reviewers (AI and FG) reviewed and extracted data independently using a standard form. The primary analysis was performed for efficacy and safety endpoints on an intention‐to‐treat basis for the study period of randomized treatment. A meta‐regression analysis was used to investigate the relationship between daily dose and clinical outcome. Results: Seven studies that fulfillled our predefined criteria were identified, for a total of 1379 patients. When all studies were combined, a statistically non‐significant reduction in the risk of VTE (OR 0.66; 95% confidence interval [CI] 0.41, 1.07) and in the risk of major bleeding (OR 0.45; 95% CI 0.18, 1.11) in favor of LMWH treatment was found. No difference in total mortality (OR 1.19; 95% CI 0.78, 1.83) or in cancer‐related mortality was observed between the LMWH and the OA treatment. Conclusions: The results of this meta‐analysis indicate that a 3‐month course of LMWH is as effective and safe as a corresponding period of OA treatment, and may thus be considered as a valuable alternative option for patients in whom OA treatment appears contraindicated or problematic.     

Hydrogels for oral delivery of therapeutic proteins

In recent years there has been significant new interest in the development of transmucosal (mostly oral) pharmaceutical formulations for the delivery of therapeutic proteins. Emphasis has been given to the molecular design of new carriers for the delivery of insulin, calcitonin and various types of interferons for the treatment of diabetes, osteoporosis, multiple sclerosis and cancer. Most popular carriers include advanced designs of swollen hydrogels prepared from neutral or intelligent polymeric networks. In this review, the most successful of such systems are presented and their promise in the field described.     

Controlled application and removal of liposomal therapeutics: Effective elimination of pegylated liposomal doxorubicin by double‐filtration plasmapheresis in vitro

Introduction: Nanoscale particle‐based drug delivery systems like long circulating liposomal doxorubicin show unique pharmacokinetic properties and improved toxicity profiles. Liposomal doxorubicin accumulates in tumor tissue due to the enhanced permeation and retention effect, but only a small fraction of a total dose reaches the tumor site. Accumulation of liposomal doxorubicin is much faster in tumor sites than in certain organs where dose limiting adverse effects occur. Finding a way to detoxify the predominant part of a given dose, circulating in the blood after accumulation is completed, will presumably reduce severe side effects during chemotherapy. Methods: Elimination properties of therapeutic used pegylated liposomal doxorubicin (Doxil®/Caelyx®) and therapeutic used double‐filtration plasmapheresis systems were evaluated in vitro and in reconstituted human blood. Results: Liposomes can be filtered by appropriate membranes without leakage of doxorubicin up to a pressure of 1 bar. At higher pressures, liposomes (～85 nm) may squeeze through much smaller pores without significant leakage of doxorubicin, whereas decreasing pore size to ～8 nm leads to increased leakage of doxorubicin. With therapeutic used apheresis systems, liposomal doxorubicin can be efficiently eliminated out of buffer medium and reconstituted human blood. No leakage of doxorubicin was detected, even when liposomes were circulating for 48 h in human plasma before apheresis. Conclusions: Convenient apheresis techniques are capable of a safe and efficient elimination of therapeutic used liposomal doxorubicin in an experimental model system. J. Clin. Apheresis, 2010. © 2010 Wiley‐Liss, Inc.     

Recent advances in the diagnosis and therapeutics for human prion diseases

Prion diseases, or transmissible spongiform encephalopathies, are fatal, neurodegenerative disorders associated with the accumulation of a misfolded infectious prion protein which is made by a posttranslational conformational change of the host-encoded cellular prion protein. A large number of studies to reveal the pathogenesis of prion diseases have been done using such experimental models as animals, cell cultures and cell-free systems over the past 30 years. The prion pathogenesis is still enigmatic, but current explosion of the knowledge about prion biology has led to the discovery of either more reliable diagnostic measurements or more beneficial therapeutic candidates. Here, the recent advances are reviewed in the diagnostics and the therapeutics for prion diseases.     

Update on perioperative bridging in patients on chronic oral anticoagulation

Oral anticoagulation (OAC) with vitamin K antagonists is commonly used for long-term prevention or treatment of arterial or venous thromboembolism. In the USA alone, approximately 250,000 patients will require temporary interruption of OAC annually. Managing anticoagulation in those patients on chronic OAC who require invasive procedures continues to be a major clinical dilemma. This article summarizes the existing evidence in light of the recommendations of the American College of Chest Physicians. Management of anticoagulation in the perioperative period will continue to be an important clinical challenge and an evolving area of research. If new oral anticoagulants are successful in replacing warfarin, the entire perioperative anticoagulation scene will change.     

Recent clinical trends in Toll-like receptor targeting therapeutics

Toll-like receptors (TLRs) are germline-encoded receptors that are central to innate and adaptive immune responses. Owing to their vital role in inflammation, TLRs are rational targets in clinics; thus, many ligands and biologics have been reported to overcome the progression of various inflammatory and malignant conditions and support the immune system. For each TLR, at least one, and often many, drug formulations are being evaluated. Ligands reported as stand-alone drugs may also be reported based on their use in combinatorial therapeutics as adjuvants. Despite their profound efficacy in TLR-modulation in preclinical studies, multiple drugs have been terminated at different stages of clinical trials. Here, TLR modulating drugs that have been evaluated in clinical trials are discussed, along with their mode of action, suggestive failure reasons, and ways to improve the clinical outcomes. This review presents recent advances in TLR-targeting drugs and provides directions for more successful immune system manipulation.     

Oral heparin administration with a novel drug delivery agent (SNAC) in healthy volunteers and patients undergoing elective total hip arthroplasty

Summary.  Background : Unfractionated heparin (UFH) is safe and effective for thromboprophylaxis, but its use is limited to parenteral administration. A novel drug delivery agent (SNAC) has been developed to accomplish the oral delivery of heparin. Objective:  This report describes the foundation for dose selection and use of oral heparin/SNAC in patients undergoing elective total hip arthroplasty (THA). Patients and methods : To develop a treatment regimen for clinical study, a multiple dose Phase I pharmacokinetic (PK) study in healthy volunteers compared oral heparin/SNAC (90 000 U heparin) with subcutaneous UFH (5000 U). On this basis, we carried out a double-blind, randomized, multicenter study comparing subcutaneous UFH (5000 U) with oral heparin/SNAC at either 60 000 or 90 000 U heparin in 123 patients undergoing elective THA. Patients received, postoperatively, one of the three treatments every 8 h for a total of 12 doses and were followed for 35 days post surgery. Results:  In the Phase I study, anti-factor Xa activity peaked at 45–60 min following oral heparin/SNAC, returning to baseline at 4 h. Results of the randomized trial in THA patients showed that venous thromboembolic events ( n  = 6), major bleeding events ( n  = 5) and need for transfusion ( n  = 23) were distributed evenly among the three treatment groups, UFH and both doses of oral heparin/SNAC. Conclusion : This is the first demonstration that oral heparin/SNAC can be safely delivered to the postoperative THA patient, and provides the basis for a larger clinical trial to assess the prophylactic efficacy of heparin/SNAC.     

Acylated non-α-amino acids as novel agents for the oral delivery of heparin sodium, USP

Ten N-acylated, non-α-amino acids have been prepared as oral delivery agents and used to demonstrate the oral delivery of heparin in vivo in rats and primates. Following the oral administration of solutions containing a combination of heparin and a delivery agent to rats or primates, significant plasma heparin concentrations were evidenced by APTT and anti-Factor Xa assays. The estimated pharmacodynamic equivalence for an oral dosing solution containing heparin and a delivery agent is 39% in primates. In vitro experiments based on heparin affinity chromatography or heparin/methylene blue complexation were also performed to begin investigation of the mechanism by which these compounds facilitate heparin oral delivery. Results of in vitro studies suggest that absorption of the drug across the gastrointestinal membrane is the result of a non-covalent interaction between heparin and the delivery agent.     

Recent advances in the search for antiviral agents against human papillomaviruses

Infection by human papillomavirus (HPV) is extremely common and associated with the development of benign warts or malignant lesions of the skin and mucosa. Infection by a high-risk (oncogenic) anogenital HPV type, most often through sexual contacts, is the starting point of virtually all cases of cervical cancers and the majority of anal cancers. The same viral types are also increasingly being linked with a subset of head-and-neck and non-melanoma skin cancers. Although prophylactic vaccines are now available to protect against the four types most commonly found in cervical and anal cancers (HPV16 and HPV18) and anogenital warts (HPV6 and HPV11), these neither protect against all genital HPVs nor are of therapeutic utility for already infected patients. Thus, the need for antiviral agents to treat HPV-associated diseases remains great, but none currently exist. This article reviews the recent progress made towards the development of antiviral agents to treat HPV infections, from target identification and validation to the discovery of lead compounds with therapeutic potential. Emphasis has been placed on novel low-molecular-weight compounds that antagonize HPV proteins or, alternatively, inhibit cellular proteins which have been usurped by papillomaviruses and are mediating their pathogenic effects.     

An Explanation of Recommendation Differences: Illustrations from Recent Atrial Fibrillation Guidelines

The development of guidelines and their use in all areas of medicine has greatly expanded in recent years. However, despite a shared evidence base, recommendations provided by different professional societies and healthcare authorities often vary considerably. The rapid advances in atrial fibrillation (AF) and the multiplicity of guidelines devoted to AF have made it particularly susceptible to this problem. Many nonmedical aspects are important in the development of guidelines, and without understanding them correct interpretation of guidelines is difficult. Conflicts of interest, the regulatory environment, and local data all influence guidelines. Nuanced wording, resource availability, and strategic purpose add complexity to guideline recommendations. This article reviews major AF guidelines from around the world and discusses aspects which have nothing to do with the scientific evidence base in order to help the practicing physician understand and make better use of differing guideline recommendations.     

低分子量肝素在血液透析应用中的评价

目的：比较低分子量肝素与普通肝素在常规血液透析抗凝中的有效性和安全性。方法：40例血液透析患分别用低分子量肝素和普通肝素抗凝进行自身对照，并作低分子肝素组与普通肝素组的组间对照。观察透析器及透析管道的凝血状态，内瘘穿刺点的压迫止血时间，抗因子Xa活性(AFXa)、凝血酶时间(TT)和活化部分凝血活酶时间(APTT)。结果：两组患均能顺利完成5小时透析，透析器及透析管道凝血程度及穿刺点压迫止血时间两组均无显差异(P＞0．05)。两组患使用低分子肝素抗凝透析结束时AFXa较血液透析前有显性差异(P＜0．001)，且透析开始后30分钟及透析结束时均明显高于普通肝素组，而APTT、TT在LMWH抗凝过程中无显延长，而普通肝素组则明显延长。结论：低分子量肝素在血液透析抗凝过程中较之普通肝素更有效，安全，方便，可替代普通肝素。     

小剂量肝素和低分子肝素治疗恶性血液病血栓前状态的临床研究

目的探讨D-二聚体(D-dimer,D-D)在恶性血液病患者中的临床意义,以及使用小剂量肝素和低分子肝素后的变化.方法正常对照20例.恶性血液病45例,分为3组:①单纯化疗组(15例);②小剂量肝素组(15例);③低分子肝素组(15例).采用酶联免疫吸附测定(ELISA)双抗夹心法对45例恶性血液病进行了D-D测定.结果恶性血液病组D-D较对照组明显增高,差异具有统计学意义(P<0.01),使用小剂量肝素和低分子肝素后D-D含量较初诊时明显降低(P<0.05),且低分子肝素组较小剂量肝素组降低更为明显(P<0.05).结论恶性血液病患者D-D含量可早期发现血栓前状态,低分子肝素较小剂量肝素具有更明显降低D-D含量的作用.低分子肝素改善血栓前状态有效、安全.