Mechanisms and translational applications of regeneration in limbs: From renewable animals to humans.

BACKGROUND: The regenerative capacity of organisms declines throughout evolution, and mammals lack the ability to regenerate limbs after injury. Past approaches to achieving successful restoration through pharmacological intervention, tissue engineering, and cell therapies have faced significant challenges. OBJECTIVES: This review aims to provide an overview of the current understanding of the mechanisms behind animal limb regeneration and the successful translation of these mechanisms for human tissue regeneration. RESULTS: Particular attention was paid to the Mexican axolotl (Ambystoma mexicanum), the only adult tetrapod capable of limb regeneration. We will explore fundamental questions surrounding limb regeneration, such as how amputation initiates regeneration, how the limb knows when to stop and which parts to regenerate, and how these findings can apply to mammalian systems. CONCLUSIONS: Given the urgent need for regenerative therapies to treat conditions like diabetic foot ulcers and trauma survivors, this review provides valuable insights and ideas for researchers, clinicians, and biomedical engineers seeking to facilitate the regeneration process or elicit full regeneration from partial regeneration events.

Salvianolic acid B protects against UVB-induced skin aging via activation of NRF2.

BACKGROUND: Prolonged exposure to sun radiation may result in harmful skin photoaging. Therefore, discovering novel anti-photoaging treatment modalities is critical. An active component isolated from Salvia miltiorrhiza (SM), Salvianolic acid B (Sal-B), is a robust antioxidant and anti-inflammatory agent. This investigation aimed to discover the therapeutic impact and pathways of salvianolic acid B for UVB-induced skin photoaging, an area that remains unexplored. METHODS: We conducted in vitro experiments on human dermal fibroblasts (HDFs) exposed to UVB radiation, assessing cellular senescence, superoxide dismutase (SOD) activity, cell viability, proliferation, migration, levels of reactive oxygen species (ROS), and mitochondrial health. The potential mechanism of Sal-B was analyzed using RNA sequencing, with further validation through Western blotting, PCR, and nuclear factor erythroid 2-related factor 2 (NRF2) silencing methods. In vivo, a model of skin photoaging induced by UVB in nude mice was employed. The collagen fiber levels were assessed utilizing hematoxylin and eosin (H&E), Masson, and Sirus red staining. Additionally, NRF2 and related gene and protein expression levels were identified utilizing PCR and Western blotting. RESULTS: Sal-B was found to significantly counteract photoaging in UVB-exposed skin fibroblasts, reducing aging-related decline in fibroblast proliferation and an increase in apoptosis. It was observed that Sal-B aids in protecting mitochondria from excessive ROS production by promoting NRF2 nuclear translocation. NRF2 knockdown experiments established its necessity for Sal-B's anti-photoaging effects. The in vivo studies also verified Sal-B's anti-photoaging efficacy, surpassing that of tretinoin (Retino-A). These outcomes offer novel insights into the contribution of Sal-B in developing clinical treatment modalities for UVB-induced photodamage in skin fibroblasts. CONCLUSION: In this investigation, we identified the Sal-B protective impact on the senescence of dermal fibroblasts and skin photoaging induced by radiation of UVB. The outcomes suggest Sal-B as a potential modulator of the NRF2 signaling pathway.

Topical Application of TT-10 Ameliorates Impaired Wound Healing.

BACKGROUND: In recent decades, chronic wounds have become an increasingly significant clinical concern due to their increasing morbidity and socioeconomic toll. However, there is currently no product available on the market that specifically targets this intricate process. One clear indicator of delayed wound repair is the inhibition of re-epithelialization. Yes-associated protein (YAP), which is a potential focal point for tissue repair and regeneration, has been shown to be prominent in several studies. In this context, we have identified the pharmacological product TT-10, which is a YAP activator, as a potential candidate for the treatment of various forms of chronic wounds. METHODS: The role of TT-10 in regulating YAP activity and subcellular localization was determined by western blotting and immunofluorescence staining. The effect of TT-10 on the biological functions of keratinocytes was assessed by proliferation, wound healing, and apoptosis assays. The impairment of YAP activity in chronic wounds was measured in human and mouse tissues. The in vivo efficacy of TT-10 was examined by gross examination, H&E staining, and measuring wound areas and gaps in normal, diabetic, and ischemic wounds. RESULTS: Our findings suggest that TT-10 facilitates the nuclear transport of YAP, consequently increasing YAP activity, which in turn increases the proliferation and migration of keratinocytes. Moreover, we showed that intracutaneous injection of TT-10 along the wound periphery promoted re-epithelization via YAP activation in the epidermis, culminating in accelerated wound closure in several chronic wound healing models. CONCLUSIONS: Our research highlights the potential of TT-10 to treat chronic wounds, which is a persistent challenge in tissue repair.

Matrix stiffness-induced α-tubulin acetylation is required for skin fibrosis formation through activation of Yes-associated protein.

Skin fibrosis, a pathological process featured by fibroblast activation and extracellular matrix (ECM) deposition, makes a significant contribution to morbidity. Studies have identified biomechanics as the central element in the complex network of fibrogenesis that drives the profibrotic feedback loop. In this study, we found that the acetylation of α-tubulin at lysine 40 (K40) was augmented in fibrotic skin tissues. Further analysis showed that α-tubulin acetylation is required for fibroblast activation, including contraction, migration, and ECM deposition. More importantly, we revealed that biomechanics-induced upregulation of K40 acetylation promotes fibrosis by mediating mechanosensitive Yes-associated protein S127 dephosphorylation and its cytoplasm nucleus shuttle. Furthermore, we demonstrated that the knockdown of α-tubulin acetyltransferase 1 could rescue the K40 acetylation upregulation caused by increased matrix rigidity and ameliorate skin fibrosis both in vivo and in vitro. Herein, we highlight the critical role of α-tubulin acetylation in matrix stiffness-induced skin fibrosis and clarify a possible molecular mechanism. Our research suggests α-tubulin acetylation as a potential target for drug design and therapeutic intervention.

Advancements in adipose-derived stem cell therapy for skin fibrosis.

Pathological scarring and scleroderma, which are the most common conditions of skin fibrosis, pathologically manifest as fibroblast proliferation and extracellular matrix (ECM) hyperplasia. Fibroblast proliferation and ECM hyperplasia lead to fibrotic tissue remodeling, causing an exaggerated and prolonged wound-healing response. The pathogenesis of these diseases has not been fully clarified and is unfortunately accompanied by exceptionally high medical needs and poor treatment effects. Currently, a promising and relatively low-cost treatment has emerged-adipose-derived stem cell (ASC) therapy as a branch of stem cell therapy, including ASCs and their derivatives-purified ASC, stromal vascular fraction, ASC-conditioned medium, ASC exosomes, etc., which are rich in sources and easy to obtain. ASCs have been widely used in therapeutic settings for patients, primarily for the defection of soft tissues, such as breast enhancement and facial contouring. In the field of skin regeneration, ASC therapy has become a hot research topic because it is beneficial for reversing skin fibrosis. The ability of ASCs to control profibrotic factors as well as anti-inflammatory and immunomodulatory actions will be discussed in this review, as well as their new applications in the treatment of skin fibrosis. Although the long-term effect of ASC therapy is still unclear, ASCs have emerged as one of the most promising systemic antifibrotic therapies under development.

Epigenetics as a versatile regulator of fibrosis.

Fibrosis, a process caused by excessive deposition of extracellular matrix (ECM), is a common cause and outcome of organ failure and even death. Researchers have made many efforts to understand the mechanism of fibrogenesis and to develop therapeutic strategies; yet, the outcome remains unsatisfactory. In recent years, advances in epigenetics, including chromatin remodeling, histone modification, DNA methylation, and noncoding RNA (ncRNA), have provided more insights into the fibrotic process and have suggested the possibility of novel therapy for organ fibrosis. In this review, we summarize the current research on the epigenetic mechanisms involved in organ fibrosis and their possible clinical applications.

Salvianolic Acid B Reduces the Inflammation of Fat Grafts by Inhibiting the NF-Kb Signalling Pathway in Macrophages.

BACKGROUND: Autologous fat grafting is a common method for soft tissue defect repair. However, the high absorption rate of transplanted fat is currently a bottleneck in the process. Excessive inflammation is one of the main reasons for poor fat transplantation. Salvianolic acid B (Sal-B) is a herbal medicine that shows promise for improving the effectiveness of fat transplantation. OBJECTIVE: The aim of this study was to improve fat graft survival by injecting Sal-B into fat grafts locally. METHODS: In vivo, 0.2 mL of Coleman fat was transplanted into nude mice along with Sal-B. The grafts were evaluated by histologic analysis at 2, 4, and 12 weeks posttransplantation and by microcomputed tomography at 4 weeks posttransplantation. In vitro ribonucleic acid sequencing, cell proliferation assays, anti-inflammatory activity assays, molecular docking studies, and kinase activity assays were performed in RAW264.7 cells to detect the potential mechanism. RESULTS: Sal-B significantly improved fat graft survival and attenuated adipose tissue fibrosis and inflammation. Sal-B also inhibited the polarization of M1 macrophages in fat grafts. In vitro, Sal-B inhibited the proliferation and activation of inflammatory pathways in RAW264.7 cells. In addition, Sal-B had an inhibitory effect on NF-κB (nuclear factor κ light polypeptide gene enhancer in B cells) signaling. This bioactivity of Sal-B may result from its selective binding to the kinase domain of the inhibitor of NF-κB kinase subunit ß. CONCLUSIONS: Sal-B could serve as a promising agent for improving the effect of fat transplantation by inhibiting the polarization of M1 macrophages through NF-κB signaling.

Monitoring diacylglycerols in biofluids by non-isotopically paired charge derivatization combined with LC-MS/MS.

Diacylglycerols (DAGs) are important lipid mediators in cellular signaling transduction and metabolism. Imbalanced production or consumption of DAGs has a negative impact on the physiological functions of the body. However, comprehensive monitoring of structurally diverse DAGs remains a daunting task due to the rapid metabolism and ion suppression characteristics in biofluids. These bottlenecks call for developing a method that enables sensitive quantification of DAGs in biological sample. In this work, a straightforward charge derivatization strategy was developed to insert a series of structure analogs charge label, i.e., N, N-dimethylglycine (DMG) and N, N-dimethylalanine (DMA), on the free hydroxyl group of the DAGs. Owing to the existence of tertiary amino groups in charge label, the mass spectrometry ionization response of the derivatized DAGs was significantly increased in comparison with traditional metal ion adducts. After charge derivatization, the specific neutral loss diagnostic ions (DMG, 103 Da and DMA, 117 Da) were captured by mass spectrometry. Then, the DMG/DMA-oriented paired multiple reaction monitoring methods based on the characteristic diagnostic ions of the derivatized DAGs have been developed as sensitive methods for the detection (detection limit = 16 aM) and quantification (quantification limit = 62.5 aM) of DAGs in serum. Moreover, the tagged 1,2-DAGs and 1,3-DAGs sn-isomers have been well separated on the reversed-phase column in combination with ultra-performance liquid chromatography. Finally, metabolic characterizations of the tagged DAGs were further explored in L-Arginine-induced acute pancreatitis mice and resveratrol treated model mice. The results indicated that 1,2-DAGs were increased in the serum of model mice relative to normal controls and resveratrol significantly altered this metabolic abnormality. The currently established DMG/DMA-oriented paired charge derivatization strategy is promising for depicting DAGs changes more accurately in metabolic studies of lipid-related diseases and accurately evaluating drug treatment strategies.

HDAC5-mediated Smad7 silencing through MEF2A is critical for fibroblast activation and hypertrophic scar formation.

Transforming growth factor-ß (TGF-ß) signaling plays a key role in excessive fibrosis. As a class IIa family histone deacetylase (HDAC), HDAC5 shows a close relationship with TGF-ß signaling and fibrosis. However, the effect and regulatory mechanism of HDAC5 in hypertrophic scar (HS) formation remain elusive. We show that HDAC5 was overexpressed in HS tissues and depletion of HDAC5 attenuated HS formation in vivo and inhibited fibroblast activation in vitro. HDAC5 knockdown (KD) significantly downregulated TGF-ß1 induced Smad2/3 phosphorylation and increased Smad7 expression. Meanwhile, Smad7 KD rescued the Smad2/3 phosphorylation downregulation and scar hyperplasia inhibition mediated by HDAC5 deficiency. Luciferase reporter assays and ChIP-qPCR assays revealed that HDAC5 interacts with myocyte enhancer factor 2A (MEF2A) suppressing MEF2A binding to the Smad7 promoter region, which results in Smad7 promoter activity repression. HDAC4/5 inhibitor, LMK235, significantly alleviated hypertrophic scar formation. Our study provides clues for the development of HDAC5 targeting strategies for the therapy or prophylaxis of fibrotic diseases.

Targeting the stem cell niche: role of collagen XVII in skin aging and wound repair.

The skin epidermis and appendages undergo ongoing renewal throughout life. Stem cells residing in the epidermis and hair follicles are pivotal for sustaining skin homeostasis. The self-renewal ability of stem cells significantly decreases during skin aging but actively increases during wound repair. Residential stem cells reside in niches that provide spatially distinct microenvironments for stem cell maintenance and function. Cell-extracellular matrix (ECM) adhesion is essential for the establishment of niche architecture. Collagen XVII (COL17), as a transmembrane protein constituting hemidesmosomes (HDs), mediates the interactions of stem cells with surrounding cells and the matrix to regulate skin homeostasis, aging and wound repair. This review focuses on the pivotal role of the niche component COL17 in stem cell maintenance and its function in regulation of skin aging and wound repair.

Measurement of Intracellular Nitric Oxide with a Quantitative Mass Spectrometry Probe Approach.

Nitric oxide (NO) is a molecule of physiological importance, and the function of NO depends on its concentration in biological systems, particularly in cells. Concentration-based analysis of intracellular NO can provide insight into its precise role in health and disease. However, current methods for detecting intracellular NO are still inadequate for quantitative analysis. In this study, we report a quantitative mass spectrometry probe approach to measure NO levels in cells. The probe, Amlodipine (AML), comprises a Hantzsch ester group that reacts with NO to form a pyridine, Dehydro Amlodipine (DAM). Quantification of DAM by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) allows specific measurement of intracellular NO levels. Notably, the AML/NO reaction proceeds rapidly (within 1 s), which is favorable for NO detection considering its large diffusivity and short half-life. Meanwhile, studies under simulated physiological conditions revealed that the AML response to NO is proportional and selective. The presented UPLC-MS/MS method showed high sensitivity (LLOQ = 0.24 nM) and low matrix interference (less than 15%) in DAM quantification. Furthermore, the mass spectrometry probe approach was demonstrated by enabling the measurement of endogenous and exogenous NO in cells. Hence, the quantitative UPLC-MS/MS method developed using AML as a probe is expected to be a new method for intracellular NO analysis.

Diagnostic fragmentation-assisted mass spectral networking coupled with in silico dereplication for deep annotation of steroidal alkaloids in medicinal Fritillariae Bulbus.

Fully understanding the chemicals in an herbal medicine remains a challenging task. Molecular networking (MN) allows to organize tandem mass spectrometry (MS/MS) data in complex samples by mass spectral similarity, which yet suffers from low coverage and accuracy of compound annotation due to the size limitation of available databases and differentiation obstacle of similar chemical scaffolds. In this work, an enhanced MN-based strategy named diagnostic fragmentation-assisted molecular networking coupled with in silico dereplication (DFMN-ISD) was introduced to overcome these obstacles: the rule-based fragmentation patterns provide insights into similar chemical scaffolds, the generated in silico candidates based on metabolic reactions expand the available natural product databases, and the in silico annotation method facilitates the further dereplication of candidates by computing their fragmentation trees. As a case, this approach was applied to globally profile the steroidal alkaloids in Fritillariae bulbus, a commonly used antitussive and expectorant herbal medicine. Consequently, a total of 325 steroidal alkaloids were discovered, including 106 cis-D/E-cevanines, 142 trans-D/E-cevanines, 29 jervines, 23 veratramines, and 25 verazines. And 10 of them were confirmed by available reference standards. Approximately 70% of the putative steroidal alkaloids have never been reported in previous publications, demonstrating the benefit of DFMN-ISD approach for the comprehensive characterization of chemicals in a complex plant organism.

Natural Xanthone α-Mangostin Inhibits LPS-Induced Microglial Inflammatory Responses and Memory Impairment by Blocking the TAK1/NF-κB Signaling Pathway.

SCOPE: The effect of α-mangostin (α-M), a polyphenolic xanthone isolated from mangostin, on lipopolysaccharide (LPS)-induced microglial activation and memory impairment is explored. The possible underlying mechanisms are also investigated. METHODS AND RESULTS: Cytokine production and activation of transforming growth factor activated kinase-1 (TAK1) and nuclear factor-κB (NF-κB) are detected by enzyme-linked immunosorbent assay (ELISA) or Western blot. Microglial migration and phagocytosis are evaluated with scratch wound-healing assay and phagocytosis of fluorescent latex beads, respectively. Learning and memory abilities of mice are evaluated with the Morris water maze test. The nanomolar (100-500 nm) α-M suppresses LPS-induced pro-inflammatory cytokine production and inducible nitric oxide synthase (iNOS) expression in microglia. It also inhibits LPS-induced microglial migration and phagocytosis. α-M rescues LPS-caused, microglia-mediated neuronal dendritic damage. Moreover, α-M represses LPS-induced toll-like receptor 4 (TLR4) expression and activation of TAK1 and NF-κB. In a mouse neuroinflammation model, α-M (50 mg kg-1 day-1 ) shows obvious anti-neuroinflammatory, neuroprotective, and memory-improving effects in vivo. CONCLUSION: α-M inhibits microglia-mediated neuroinflammation and prevents neurotoxicity and memory impairment from inflammatory damage. These results indicate that α-M has great potential to be used as a nutritional preventive strategy for neuroinflammation-related neurodegenerative disorders such as Alzheimer's disease.

Enhancing enrichment ability of ZIF-8 mixed matrix membrane microextraction by reverse micelle strategy for analysis of multiple ionizable bioactive components in biological samples.

Recent research aimed at the design of mixed-matrix membrane (MMM) to be used for microextraction emphasized on membrane extraction phase with high surface area and porosity. This study explored the influence that surfactants have on MMM extraction efficiency for the first time. The zeolitic imidazolate framework 8-based MMM (ZIF-8-MMM) was synthesized by in situ self-assembly of ZIF-8 on the inner wall of a hollow fiber membrane with the aim of fabricating a microextraction device. By prompting the encapsulation of ionizable analytes in the polar core of reverse micelles, the presence of surfactants in extraction solvent assisted the dissolution of analytes in the fiber membrane lumen and enhanced their adsorption onto ZIF-8. Notably, hereby a microextraction method based on the novel ZIF-8-MMM-reverse micelle (ZIF-8-MMM-RM) system was developed and employed for the extraction and quantitation of two alkaloids (berberine and jatrorrhizine) and two flavonoids (wogonin and wogonoside) in biological samples. The main factors affecting microextraction performance, identity of the extraction solvent, surfactant concentration, sample solution pH and extraction time, were investigated in detail. The method showed good linearity (r2 > 0.99) and repeatability (RSD < 10%), low limits of detection (0.10-0.31 ng mL-1) and high relative recoveries (90.03-98.84%). The enrichment factor values ranged between 48.47 and 54.96. Reverse micelle formation prompted by surfactant addition was demonstrated to effectively assist the extraction of multiple ionizable analytes from biological samples, resulting in a marked improvement of ZIF-8-MMM extraction performance.

Untargeted metabolomics coupled with chemometric analysis reveals species-specific steroidal alkaloids for the authentication of medicinal Fritillariae Bulbus and relevant products.

Authentication of original species is embedded in the quality control system of herbal medicines. In this work, ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based untargeted metabolomics coupled with chemometric analysis was utilized for the precise authentication of the Fritillaria species for both raw materials and commercial products. First, a stepwise difference-enlarging chemometric analysis strategy was proposed to analyze eight medicinal Fritillaria species. Subsequently, 21 species-specific markers were discovered and the specificity was investigated under different sample preparation methods. Finally, the obtained species-specific markers were successfully utilized to identify the Fritillaria species in commercially relevant products. This work is the first to report robust and specific markers for authentication of Fritillaria products, showing promise for tracking the supply chain of herbal suppliers.

A novel liquid-liquid-solid microextraction strategy for bio-sample preparation by in situ self-assembly of zeolitic imidazolate framework 8 on hollow fiber membrane.

A novel liquid-liquid-solid membrane microextraction (LLSMME) method which integrates hollow fiber liquid phase microextraction (HF-LPME) and solid phase microextraction (SPME) was developed for bio-sample preparation. The homogeneous zeolitic imidazolate framework 8 mixed matrix membrane (ZIF-8-MMM) was prepared by in situ self-assembly of ZIF-8 on the inner surface of hollow fiber membrane and employed as a flexible LLSMME device. Incorporating the advantages of both HF-LPME and SPME, the as-fabricated ZIF-8-MMM exhibited excellent performance on the extraction and preconcentration of small molecule drugs of different polarity from complex biological matrices. As a case study, ZIF-8-MMM-based LLSMME coupled with UPLC-MS/MS were developed and validated for determination of ibuprofen, simvastatin and ranitidine at trace levels in rat plasma. The method showed good linearity (r2 > 0.99) and repeatability (RSD < 15%), low limits of detection (2-3 ng mL-1) and high relative recoveries (97.42-103.8%). The enrichment factors were between 87.3 and 112.6. Our study provided a promising strategy for developing more efficient, cost-effective and environmentally friendly technique for bio-sample pretreatment.

Thermosensitive In Situ Gel Based on Solid Dispersion for Rectal Delivery of Ibuprofen.

The objective of this study was to develop a thermosensitive in situ gel based on solid dispersions (SDs) for rectal delivery of ibuprofen (IBU). Thermosensitive (poloxamer 407) and mucoadhesive (hydroxypropylmethyl cellulose E5 and sodium alginate) polymers were used to prepare the in situ gel and the sol-gel transition temperature (T sol-gel) and gel strength were optimized. The in vitro release performance and in vivo pharmacokinetic properties of the in situ gel after their rectal administration to rabbits were investigated. Compared with the solid suppository, the cumulative release of the IBU SDs loaded in situ gel was significantly increased. The in vivo pharmacokinetics indicated that in situ gel had a higher peak plasma concentration (C max) and area under the curve (AUC(0-∞)) in plasma than the solid suppositories. Histopathology results showed that the IBU in situ gel given at a dose of 15 mg/kg did not produce any irritation. In conclusion, this study suggested that the in situ gel could be an effective rectal formulation for IBU.

Quantitative Detection of Ambroxol in Human Plasma Using HPLC-APCI-MS/MS: Application to a Pharmacokinetic Study.

In this study, a rapid and reliable high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of ambroxol in human plasma was developed and validated using palmatine as an internal standard (IS). Ambroxol and IS were extracted from 200 µL of human plasma via a simple protein precipitation preparation. Chromatographic separation was achieved on a Platisil C18 column (150 × 4.6 mm, 5 µm) using methanol-0.01% formic acid (70:30, v/v) as the mobile phase at a flow rate of 0.6 mL/min under an isocratic condition. The MS acquisition m/z 379 → 264 for ambroxol and 352 → 336 for IS was performed by atmospheric-pressure chemical ionization (APCI) mass spectrometry in selected reaction monitoring mode. The calibration curve for ambroxol was linear over the concentration range of 2.500 - 180.0 ng/mL. The matrix effects of ambroxol ranged from 104.6 to 112.7%. This fully validated method was successfully applied to a pharmacokinetic study of ambroxol in humans after oral administration of ambroxol at a single dose of 75 mg.

Simultaneous determination of seven alkaloids from Rhizoma Corydalis Decumbentis in rabbit aqueous humor by LC-MS/MS: Application to ocular pharmacokinetic studies.

This study aims to establish a fast and sensitive LC-MS/MS method for simultaneous determination of seven alkaloids from Rhizoma Corydalis Decumbentis in rabbit aqueous humor. Aqueous humor samples were processed by protein precipitation and then separated on a Thermo Syncronis C18 column (50mm×2.1mm, 5µm) with a mobile phase using acetonitrile-0.05% formic acid (28:72, v/v). Detection of the analytes and the internal standard (coptisine) were performed in positive electrospray ionization with selected reaction monitoring. The method showed good linearity (r>0.9931) for all the seven alkaloids. This fully validated method was applied to the studies of aqueous humor pharmacokinetics of seven alkaloids from Rhizoma Corydalis Decumbentis and the effects of borneol on corneal penetration of these alkaloids into aqueous humor. This is the first work that presents a reliable LC-MS/MS method for simultaneous determination of seven alkaloids in rabbit aqueous humor and its application of ocular pharmacokinetics of seven alkaloids from Rhizoma Corydalis Decumbentis.

Experimental observations and dissipative particle dynamic simulations on microstructures of pH-sensitive polymer containing amorphous solid dispersions.

Amorphous solid dispersion (ASD) technique is an effective strategy to increase the dissolution rate of poorly soluble drugs. However, it is inherently unstable, and the molecular basis for achieving kinetic stability is not well understood. In this study, lacidipine-Eudragit_E_100 solid dispersions with 20% drug loading were prepared using the solvent evaporation. Dissolution tested showed that ASD had a significantly high rate, which was dependent on the pH of the medium. Based on time-dependent measurement of supersaturation and particle size, inhibition of crystal growth by Eudragit_E_100 differed at pH 1.2 and 6.8 to a great extent. Dissipative particle dynamic (DPD) simulation revealed that at pH 1.2, the swollen microstructures of the particles were associated with rapid drug release. At pH 6.8, a compacted microstructure of small amorphous particle-aggregated large particles was associated with slow dissolution. The DPD simulation provides insight into the structural basis for experimental observations, and thus is a useful tool to investigate the microstructures of ASD.