scholarly journals Noninvasive Evaluation of Injectable Chitosan/Nano-Hydroxyapatite/Collagen Scaffold via Ultrasound

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Yan Chen ◽  
Songjian Li ◽  
Xiaoming Li ◽  
Yichen Zhang ◽  
Zhi Huang ◽  
...  

To meet the challenges of designing anin situforming scaffold and regenerating bone with complex three-dimensional (3D) structures, anin situforming hydrogel scaffold based on nano-hydroxyapatite (nHA), collagen (Col), and chitosan (CS) was synthesized. Currently, only a limited number of techniques are available to mediate and visualize the injection process of the injectable biomaterials directly and noninvasively. In this study, the potential of ultrasound for the quantitativein vivoevaluation of tissue development in CS/nHAC scaffold was evaluated. The CS/nHAC scaffold was injected into rat subcutaneous tissue and evaluated for 28 days. Quantitative measurements of the gray-scale value, volume, and blood flow of the scaffold were evaluated using diagnostic technique. This study demonstrates that ultrasound can be used to noninvasively and nondestructively monitor and evaluate thein vivocharacteristics of injectable bone scaffold. In comparison to the CS, the CS/nHAC scaffold showed a greater stiffness, less degradation rate, and better blood supply in thein vivoevaluation. In conclusion, the diagnostic ultrasound method is a good tool to evaluate thein vivoformation of injectable bone scaffolds and facilitates the broad use to monitor tissue development and remodeling in bone tissue engineering.

Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.


Author(s):  
Greg V. Martin ◽  
Ann L. Hubbard

The microtubule (MT) cytoskeleton is necessary for many of the polarized functions of hepatocytes. Among the functions dependent on the MT-based cytoskeleton are polarized secretion of proteins, delivery of endocytosed material to lysosomes, and transcytosis of integral plasma membrane (PM) proteins. Although microtubules have been shown to be crucial to the establishment and maintenance of functional and structural polarization in the hepatocyte, little is known about the architecture of the hepatocyte MT cytoskeleton in vivo, particularly with regard to its relationship to PM domains and membranous organelles. Using an in situ extraction technique that preserves both microtubules and cellular membranes, we have developed a protocol for immunofluorescent co-localization of cytoskeletal elements and integral membrane proteins within 20 µm cryosections of fixed rat liver. Computer-aided 3D reconstruction of multi-spectral confocal microscope images was used to visualize the spatial relationships among the MT cytoskeleton, PM domains and intracellular organelles.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Robert J. Francis ◽  
Gillian Robb ◽  
Lee McCann ◽  
Bhagwati Khatri ◽  
James Keeble ◽  
...  

AbstractTuberculosis (TB) preclinical testing relies on in vivo models including the mouse aerosol challenge model. The only method of determining colony morphometrics of TB infection in a tissue in situ is two-dimensional (2D) histopathology. 2D measurements consider heterogeneity within a single observable section but not above and below, which could contain critical information. Here we describe a novel approach, using optical clearing and a novel staining procedure with confocal microscopy and mesoscopy, for three-dimensional (3D) measurement of TB infection within lesions at sub-cellular resolution over a large field of view. We show TB morphometrics can be determined within lesion pathology, and differences in infection with different strains of Mycobacterium tuberculosis. Mesoscopy combined with the novel CUBIC Acid-Fast (CAF) staining procedure enables a quantitative approach to measure TB infection and allows 3D analysis of infection, providing a framework which could be used in the analysis of TB infection in situ.


Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 624
Author(s):  
Qiang Liu ◽  
Tian Zhao ◽  
Xianning Wang ◽  
Zhongyao Chen ◽  
Yawei Hu ◽  
...  

Three-dimensional cultured patient-derived cancer organoids (PDOs) represent a powerful tool for anti-cancer drug development due to their similarity to the in vivo tumor tissues. However, the culture and manipulation of PDOs is more difficult than 2D cultured cell lines due to the presence of the culture matrix and the 3D feature of the organoids. In our other study, we established a method for lung cancer organoid (LCO)-based drug sensitivity tests on the superhydrophobic microwell array chip (SMAR-chip). Here, we describe a novel in situ cryopreservation technology on the SMAR-chip to preserve the viability of the organoids for future drug sensitivity tests. We compared two cryopreservation approaches (slow freezing and vitrification) and demonstrated that vitrification performed better at preserving the viability of LCOs. Next, we developed a simple procedure for in situ cryopreservation and thawing of the LCOs on the SMAR-chip. We proved that the on-chip cryopreserved organoids can be recovered successfully and, more importantly, showing similar responses to anti-cancer drugs as the unfrozen controls. This in situ vitrification technology eliminated the harvesting and centrifugation steps in conventional cryopreservation, making the whole freeze–thaw process easier to perform and the preserved LCOs ready to be used for the subsequent drug sensitivity test.


2007 ◽  
Vol 13 (4) ◽  
pp. 267-271 ◽  
Author(s):  
Jessica L. Franchini ◽  
John T. Propst ◽  
Gerald R. Comer ◽  
Michael J. Yost

A growing problem in cardiac drug toxicity has been blamed on the lack of adequate testing prior to authorization for prescription use. This study offers an effective alternative to the current method ofin vivopharmaceutical testing, which is time and cost prohibitive. We have accomplished this by developing the novel three-dimensional heart tube model. At the “heart” of our model lies our patented collagen scaffold that enables the cardiac myocytes to display anin vivo–like architecture. The cardiac myocytes were cocultured with the collagen tube for a period of 5 weeks, resulting in the heart tubes. Our heart tubes were treated with specific drugs (nifedipine, isoproterenol, and lidocaine) at varying concentrations. The percent of apoptotic cells was calculated based on observing the number of cells that labeled positive for caspase-3 via confocal microscopy. All three drugs exhibited negative effects at high concentrations in that the number of living cells decreased. Lidocaine showed an increase in apoptosis at concentrations of 75 μM and above. This may indicate that certain drugs have a minimum concentration level that must be reached before the cells experience apoptosis from the toxic levels.


2021 ◽  
Author(s):  
Zhenhua Zhao ◽  
Mang Wang ◽  
Fei Shao ◽  
Ge Liu ◽  
Junlei Li ◽  
...  

Abstract The ideal scaffold material of angiogenesis should have mechanical strength and provide appropriate physiological microporous structures to mimic the extracellular matrix environment. In this study, we constructed an integrated three-dimensional scaffold material using porous tantalum(pTa), gelatin nanoparticles (GNPs) hydrogel, and seeded with bone marrow mesenchymal stem cells (BMSCs)-derived endothelial cells (ECs) for vascular tissue engineering. The characteristics and biocompatibility of pTa and GNPs hydrogel were evaluated by mechanical testing, scanning electron microscopy, cell counting kit, and live-cell assay. The BMSCs-derived ECs were identified by flow cytometry and angiogenesis assay. BMSCs-derived ECs were seeded on the pTa-GNPs hydrogel scaffold and implanted subcutaneously in nude mice. Four weeks after the operation, the scaffold material was evaluated by histomorphology. The superior biocompatible ability of pTa-GNPs hydrogel scaffold was observed. Our in vivo results suggested that 28 days after implantation, the formation of the stable capillary-like network in scaffold material could be promoted significantly. The novel, integrated pTa-GNPs hydrogel scaffold is biocompatible with the host, and exhibits biomechanical and angiogenic properties. Moreover, combined with BMSCs-derived ECs, it could construct vascular engineered tissue in vivo. This study may provide a basis for applying pTa in bone regeneration and autologous BMSCs in tissue-engineered vascular grafts.


2021 ◽  
Author(s):  
Alexandre SOUCHAUD ◽  
Arthur BOUTILLON ◽  
Gaëlle CHARRON ◽  
Atef ASNACIOS ◽  
Camille NOÛS ◽  
...  

To investigate the role of mechanical constraints in morphogenesis and development, we develop a pipeline of techniques based on incompressible elastic sensors. These techniques combine the advantages of incompressible liquid droplets, which have been used as precise in situ shear stress sensors, and of elastic compressible beads, which are easier to tune and to use. Droplets of a polydimethylsiloxane (PDMS) mix, made fluorescent through specific covalent binding to a rhodamin dye, are produced by a microfluidics device. The elastomer rigidity after polymerization is adjusted to the tissue rigidity. Its mechanical properties are carefully calibrated in situ, for a sensor embedded in a cell aggregate and submitted to uniaxial compression. The local shear stress tensor is retrieved from the sensor shape, accurately reconstructed through an active contour method. In vitro, within cell aggregates, and in vivo, in the prechordal plate of the Zebrafish embryo during gastrulation, our pipeline of techniques demonstrates its efficiency to directly measure the three dimensional shear stress repartition within a tissue, and its time evolution.


2010 ◽  
Vol 190 (4) ◽  
pp. 613-621 ◽  
Author(s):  
Julio O. Ortiz ◽  
Florian Brandt ◽  
Valério R.F. Matias ◽  
Lau Sennels ◽  
Juri Rappsilber ◽  
...  

Ribosomes arranged in pairs (100S) have been related with nutritional stress response and are believed to represent a “hibernation state.” Several proteins have been identified that are associated with 100S ribosomes but their spatial organization has hitherto not been characterized. We have used cryoelectron tomography to reveal the three-dimensional configuration of 100S ribosomes isolated from starved Escherichia coli cells and we have described their mode of interaction. In situ studies with intact E. coli cells allowed us to demonstrate that 100S ribosomes do exist in vivo and represent an easily reversible state of quiescence; they readily vanish when the growth medium is replenished.


2012 ◽  
Vol 23 (3) ◽  
pp. 423-432 ◽  
Author(s):  
Aurélie Bertin ◽  
Michael A. McMurray ◽  
Jason Pierson ◽  
Luong Thai ◽  
Kent L. McDonald ◽  
...  

Septins are conserved GTP-binding proteins involved in membrane compartmentalization and remodeling. In budding yeast, five mitotic septins localize at the bud neck, where the plasma membrane is enriched in phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P2). We previously established the subunit organization within purified yeast septin complexes and how these hetero-octamers polymerize into filaments in solution and on PtdIns4,5P2-containing lipid monolayers. How septin ultrastructure in vitro relates to the septin-containing filaments observed at the neck in fixed cells by thin-section electron microscopy was unclear. A morphological description of these filaments in the crowded space of the cell is challenging, given their small cross section. To examine septin organization in situ, sections of dividing yeast cells were analyzed by electron tomography of freeze-substituted cells, as well as by cryo–electron tomography. We found networks of filaments both perpendicular and parallel to the mother–bud axis that resemble septin arrays on lipid monolayers, displaying a repeat pattern that mirrors the molecular dimensions of the corresponding septin preparations in vitro. Thus these in situ structures most likely represent septin filaments. In viable mutants lacking a single septin, in situ filaments are still present, although more disordered, consistent with other evidence that the in vivo function of septins requires filament formation.


1987 ◽  
Vol 1 (2) ◽  
pp. 306-313 ◽  
Author(s):  
W.E. Brown ◽  
N. Eidelman ◽  
B. Tomazic

What are biominerals and how are they formed? It is usually assumed: (i) that the prototype for most apatitic biominerals is hydroxyapatite (OHAp), Ca5(PO4) 3OH; and (ii) that the OHAp structure has been modified by the presence of impurity ions and vacancy defects in specific OHAp lattice sites. The usual answer, at least implicitly, to the second question is that the apatitic mineral is formed directly by the precipitation of ions from the surrounding solution. Our answers are: (i) that apatitic biominerals are formed through a precursor mechanism in which octacalcium phosphate (OCP), Ca8H 2(PO4)6·5H2O, precipitates first and then hydrolyzes ireversibly in situ to a transition product intermediate to OCP and OHAp; and (ii) that this product, "octacalcium phosphate hydrolyzate" (OCPH), may contain (a) OHAp-like and OCP-like domains in varying amounts, (b) vacancy defects and impurity ions in lattice sites in these domains, and (c) various kinds of one-, two-, and three-dimensional defects which are not present in either the OHAp or the OCP lattice, these defects being formed during the in situ hydrolysis step. A calcification model of this type was first proposed in 1957, but full acceptance was delayed because most of the evidence was circumstantial and in vitro in nature. The situation has changed radically because of three unrelated studies that are in vivo in nature but lead to the same conclusion: I. 32P-pyrolysis studies of rat enamel: The results clearly demonstrated that an acidic calcium phosphate precursor was involved. II. Precipitation of calcium phosphates in serum. Ultrafiltered serum was equilibrated with brushite. Subsequent changes in the ionic concentrations revealed that OCP was formed at first and then hydrolyzed to a more basic form, OCPH, but never reached the solubility of OHAp. III. Physicochemical properties of cardiovascular biominerals: We recently characterized biominerals in cardiovascular deposits in an encompassing variety of ways. As an overall conclusion, OCPH was the prototype most compatible with the data [including indices of refraction, solubility, P2O74- formation on pyrolysis, thermogravimetric analysis (TGA) measurements, presence of water, and incorporation of CO32-, Na+, and Mg2+]. This calcification model has important consequences relative to all kinds of calcification and decalcification processes, including those of enamel.


Sign in / Sign up

Export Citation Format

Share Document