Renal Proximal Tubular Epithelial Cells: From Harvesting to Use in Studies

The kidneys are the body's main excretion organ with several additional functions, and the nephron represents their central structural unit. It is comprised of endothelial, mesangial, glomerular, and tubular epithelial cells, as well as podocytes. Treatment of acute kidney injury or chronic kidney disease (CKD) is complex due to broad etiopathogenic mechanisms and limited regeneration potential as kidney cells finish their differentiation after 34 weeks of gestation. Despite the ever-increasing prevalence of CKD, very limited treatment modalities are available. The medical community should therefore strive to improve existing treatments and develop new ones. Furthermore, polypharmacy is present in most CKD patients, while current pharmacologic study designs lack effectiveness in predicting potential drug-drug interactions and the resulting clinically relevant complications. An opportunity for addressing these issues lies in developing in vitro cell models based on patient-derived renal cells. Currently, several protocols have been described for isolating desired kidney cells, of which the most isolated are the proximal tubular epithelial cells. These play a significant role in water homeostasis, acid-base control, reabsorption of compounds, and secretion of xenobiotics and endogenous metabolites. When developing a protocol for the isolation and culture of such cells, one must focus on several steps. These include harvesting cells from biopsy specimens or after nephrectomies, using different digestion enzymes and culture mediums to facilitate the selective growth of only the desired cells. The literature reports several existing models, from simple 2D in vitro cultures to more complex ones created with bioengineering methods, such as kidney-on-a-chip models. While their creation and use depend on the target research, one should consider factors such as equipment, cost, and, even more importantly, source tissue quality and availability.

Association between umbilical cord vitamin D levels and adverse neonatal outcomes

Objective

We investigated the associations between cord blood concentration of 25-hydroxyvitamin D [25(OH)D], neonatal outcomes, and the risk of hospitalization during the first year of life.

Methods

A total of 402 newborn infants and their mothers were prospectively enrolled and divided in four groups according to season of the year. We determined 25(OH)D serum concentrations from maternal–neonatal pairs at delivery by electrochemiluminescence immunoassay. Cut-offs at 25, 50, and 75 nmol/L defined vitamin D status, corresponding to deficiency, insufficiency, and sufficiency, respectively. Crude odds ratio (cOR) and 95% confidence intervals (CI) were estimated using logistic regression.

Results

Vitamin D severe deficiency (i.e., <25 nmol/L) was present in 18% of newborns. Cord blood severe deficiency was associated with an increased risk of preterm birth (cOR 3.6, 95% CI: 1.1–12.2), neonatal respiratory distress syndrome (cOR 5.9, 95% CI: 1.1–33.2), and increased risk of hospitalization during the first year of life because of acute respiratory infection (cOR 3.9, 95% CI: 1.4–10.6) or acute gastroenterocolitis (cOR 5.2, 95% CI: 1.4–19.1).

Conclusion

Cord blood vitamin D deficiency is associated with increased risk of preterm birth, neonatal respiratory distress syndrome, and hospitalization during the first year of life.

The Isolation of Human Glioblastoma Cells: An Optimised Protocol

OBJECTIVE

The aim of this study was to establish an optimised protocol for glioblastoma (GBM) cell isolation from brain resection samples, with a high yield and low risk for contamination.

METHODS

Human GBM cells can be obtained following cranial tumour operations. In sterile conditions, the fragments of viable tissue removed during surgery were collected. The tissue was cut and mechanically coarsely decomposed. The sediment was harvested after centrifugation, the cells were seeded in suspension, and supplemented with a special medium (Advanced DMEM) containing high level nutrients and antibiotics.

RESULTS

In an appropriate environment, the isolated cells retained viability and proliferated quickly. Attachments were observed after ten hours, and proliferation after two days. The time to full confluence was about one week. The cells were stable. Under standard culture conditions, cell proliferation and cluster formation were observed. Cell viability was 95%.

CONCLUSION

The protocol described for isolation is easy, quick and affordable, leading to stable GBM cells. The isolation technique provides sufficient quantities of isolated cells that may be used as an important new tool for in vitro research. The availability of this system will permit the study of cell properties, biochemical aspects, and provides the potential of therapeutic candidates for pathological disorders in a well-controlled environment.

Optimised isolation and characterisation of adult human astrocytes from neurotrauma patients

BACKGROUND

Astrocytes are the main cellular constituent in the central nervous system. Astrocyte cultures from rodent brains are most commonly used in the experimental practice. However, important differences between rodent and human astrocytes exist. The aim of this study was to develop an improved protocol for routine preparation of primary astrocyte culture from adult human brain, obtained after trauma.

NEW METHOD

Tissue obtained during neurotrauma operation was mechanically decomposed and centrifuged. The cell sediment was resuspended in cell culture medium, plated in T25 tissue flasks and incubated for one month at 37 °C in 5% CO_2. The medium was replaced twice weekly and microglia were removed. Once confluent, the purity of cultures was assessed. The culture was characterised immunocytochemically for specific astrocytic markers (GFAP, GLAST and S100B). Cell morphology was examined through the actin cytoskeleton labelling with fluorescent phalloidin.

RESULTS

Under basal conditions, adult astrocytes exhibited astrocyte-specific morphology and expressed specific markers. Approximately 95% of cells were positive for the main glial markers (GFAP, GLAST, S100B).

COMPARISON WITH EXISTING METHOD

We established an easy and cost-effective method for a highly enriched primary astrocyte culture from adult human brain.

CONCLUSION

The isolation technique provides sufficient quantities of isolated cells. The culture obtained in this study exhibits the biochemical and physiological properties of astrocytes. It may be useful for elucidating the mechanisms related to the adult brain, exploring changes between neonatal and adult astrocytes, novel therapeutic targets, cell therapy experiments, as well as investigating compounds involved in cytotoxicity and cytoprotection.

Intervertebral disc tissue engineering: A brief review

Intervertebral disc (IVD) degeneration (IDD) is associated with low back pain and significantly affects the patient's quality of life. Degeneration of the IVD alters disk height and the mechanics of the spine, leading to chronic segmental spinal instability. The pathophysiology of IVD disease is still not well understood. Current therapies for IDD include conservative and invasive approaches, but none of those treatments are able to restore the disc structure and function. Recently, tissue engineering techniques emerged as a possible approach to treat IDD, by replacing a damaged IVD with scaffolds and appropriate cells. Advances in manufacturing techniques, material processing and development, surface functionalization, drug delivery systems and cell incorporation furthered the development of tissue engineering therapies. In this review, biomaterial scaffolds and cell-based therapies for IVD regeneration are briefly discussed.

Low-molecular-weight sulfonated chitosan as template for anticoagulant nanoparticles

PURPOSE

In this work, low-molecular-weight sulfoethyl chitosan (SECS) was used as a model template for the generation of silver core-shell nanoparticles with high potential as anticoagulants for medical applications.

MATERIALS AND METHODS

SECS were synthesized by two reaction pathways, namely Michael addition and a nucleophilic substitution with sodium vinylsulfonate or sodium 2-bromoethanesulfonate (NaBES). Subsequently, these derivatives were used as reducing and capping agents for silver nanoparticles in a microwave-assisted reaction. The formed silver-chitosan core-shell particles were further surveyed in terms of their anticoagulant action by different coagulation assays focusing on the inhibition of either thrombin or cofactor Xa.

RESULTS

In-depth characterization revealed a sulfoalkylation of chitosan mainly on its sterically favored O6-position. Moreover, comparably high average degrees of substitution with sulfoethyl groups (DSSE) of up to 1.05 were realized in reactions with NaBES. The harsh reaction conditions led to significant chain degradation and consequently, SECS exhibits masses of <50 kDa. Throughout the following microwave reaction, stable nanoparticles were obtained only from highly substituted products because they provide a sufficient charge density that prevented particles from aggregation. High-resolution transmission electron microscopy images reveal that the silver core (diameter ~8 nm) is surrounded by a 1-2 nm thick SECS layer. These core-shell particles and the SECS itself exhibit an inhibiting activity, especially on cofactor Xa.

CONCLUSION

This interesting model system enabled the investigation of structure-property correlations in the course of nanoparticle formation and anticoagulant activity of SECS and may lead to completely new anticoagulants on the basis of chitosan-capped nanoparticles.

Gold nanoparticles in the engineering of antibacterial and anticoagulant surfaces

Simultaneous antibacterial and anticoagulant surfaces have been prepared by immobilization of engineered gold nanoparticles onto different kinds of surfaces. The gold nanoparticle core is surrounded by a hemocompatible, anticoagulant polysaccharide, 6-O chitosan sulfate, which serves as reduction and stabilizing agent for the generation of gold nanoparticles in a microwave mediated reaction. The particle suspension shows anticoagulant activity, which is investigated by aPTT and PT testing on citrated blood samples of three patients suffering from congenital or acquired bleeding disorders. The amount of nanoparticles deposited on the surfaces is quantified by a quartz crystal microbalance with dissipation unit. All gold containing surfaces exhibit excellent antimicrobial properties against the chosen model organism, Escherichia coli MG 1655 [R1-16]. Moreover, blood plasma coagulation times of the surfaces are increased after deposition of the engineered nanoparticles as demonstrated by QCM-D.

Vitrification from solution in restricted space: Formation and stabilization of amorphous nifedipine in a nanoporous silica xerogel carrier

PURPOSE

The goal was to find thermodynamic criteria that must be satisfied in order to prevent formation of crystalline state of drugs within a confined space (e.g., nanopores of inorganic solid). Similarly, criteria that lead to stabilization of amorphous drug within such pores were investigated.

METHODS

In the theoretical part, the classical thermodynamics of nucleation is applied to the conditions of a restricted space. The theoretical findings are verified using porous silica as a carrier and nifedipine as a model drug. The amorphicity of the latter is checked using XRD and thermal analysis (DTA, DSC) in combination with BET measurements.

RESULTS

It is shown that there exists a critical pore radius of a host below which the entrapped substance will solidify in an amorphous form. There also exists a critical pore radius below which the entrapped amorphous solid will not be able to crystallize. Specifically, incorporation of NIF into a silica xerogel with an average pore diameter of about 2.5 nm produces and stabilizes its amorphous form.

CONCLUSION

Entrapment of drugs into solid nanoporous carriers could be regarded as a potentially useful and simple method for production and/or stabilization of non-crystalline forms of a wide range of drugs.

Novel hybrid silica xerogels for stabilization and controlled release of drug

PURPOSE

The goal was to show that incorporation of a model drug into a porous solid matrix with small enough pores should lead to composites in which the drug would be in the amorphous rather than in the crystalline state. Due to spatial constraints, the amorphous state was expected to be temporally highly stable.

METHODS

As a porous solid matrix silica was selected, while nifedipine served as a model drug. The silica-drug composites were prepared using a sol-gel procedure at conditions which yielded pores in the range 2-3 nm. To tune the properties of composites, two silica precursors were combined: tetraethoxysilane (TEOS) and bis-1,2-(triethoxysilyl)ethane (BTSE).

RESULTS

In all composites the amorphous state of nifedipine was proven using several analytical methods. The amorphicity was preserved for at least several months. Drug incorporation into purely TEOS-based silica decreased significantly the release rate. Loosening the structure by addition of BTSE, while preserving the amorphicity, increased the drug dissolution rate. The dissolution behaviour was explained using a combination of the Noyes-Whitney and power law model.

CONCLUSION

The observed release patterns could be interesting for therapies requiring a high initial drug concentration in blood plasma, followed by a slower release rate of the remaining drug.