scholarly journals Innervation of a Prefabricated Flap: A New Experimental Model

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Marco Romeo ◽  
Giuseppe Cuccia ◽  
Shan Shan Qiu ◽  
Stefania Raimondo ◽  
Stefano Geuna ◽  
...  
Keyword(s):  
Wallerian Degeneration ◽  
Collagen Scaffold ◽  
Collagen Matrix ◽  
Acellular Matrix ◽  
The Matrix ◽  
Adequate Blood Supply ◽  
Flow Through ◽  
Cell Colonization ◽  
Direct Nerve ◽  
Prefabricated Flap

Introduction. Flap innervation by neoaxonogenesis is a promising field of investigation. The authors evaluated the possibility of innervating an acellular collagen scaffold as component of a potential prefabricated flap.Materials and Methods. Collagen matrix sheets were implanted around the femoral bundle of a murine model to produce two flaps on proximal and distal nerve stumps based on a flow-through model. After thirty days, nerve regeneration and integration into the collagen matrix were evaluated. The specimens were microscopically analyzed to study Schwann cell colonization and axonal integration with the matrix. Axonal count and density were assessed and statistically evaluated.Results. Qualitative structural and ultrastructural evaluation indicated integration, with axonal fibers merged within the collagen matrix, along with a newly formed vascular network on the proximal flap. Wallerian degeneration occurred inside the distal chamber. Axonal count and density did not show statistically significant differences between the nerve inside the proximal flap and the control side.Conclusions. Innervation of an acellular matrix can be obtained by direct nerve stump implantation. The flow-through system was relatively easy to build and reliable to provide adequate blood supply. The collagen scaffold may be a promising support or further studies of preinnervated microsurgical flaps.

A Novel Coreflood Test to Evaluate EOR Potential of Wettability-Altering Surfactants in Oil-Wet Heterogeneous Carbonate Reservoirs

2021 ◽  
Author(s):  
Yue Shi ◽  
Kishore Mohanty ◽  
Manmath Panda
Keyword(s):  
Oil Recovery ◽  
Carbonate Reservoirs ◽  
Wettability Alteration ◽  
Low Permeability ◽  
High Permeability ◽  
Matrix Permeability ◽  
Rock Heterogeneity ◽  
The Matrix ◽  
Flow Through ◽  
Main Factors

Abstract Oil-wetness and heterogeneity (i.e., existence of low and high permeability regions) are two main factors that result in low oil recovery by waterflood in carbonate reservoirs. The injected water is likely to flow through high permeability regions and bypass the oil in low permeability matrix. In this study, systematic coreflood tests were carried out in both "homogeneous" cores and "heterogeneous" cores. The heterogeneous coreflood test was proposed to model the heterogeneity of carbonate reservoirs, bypassing in low-permeability matrix during waterfloods, and dynamic imbibition of surfactant into the low-permeability matrix. The results of homogeneous coreflood tests showed that both secondary-waterflood and secondary-surfactant flood can achieve high oil recovery (>50%) from relatively homogenous cores. A shut-in phase after the surfactant injection resulted in an additional oil recovery, which suggests enough time should be allowed while using surfactants for wettability alteration. The core with a higher extent of heterogeneity produced lower oil recovery to waterflood in the coreflood tests. Final oil recovery from the matrix depends on matrix permeability as well as the rock heterogeneity. The results of heterogeneous coreflood tests showed that a slow surfactant injection (dynamic imbibition) can significantly improve the oil recovery if the oil-wet reservoir is not well-swept.

scholarly journals Experimental Study of Rainfall Infiltration in an Analog Fracture-matrix System

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhen Zhong ◽  
Huicai Gao ◽  
Yunjin Hu
Keyword(s):  
Unsaturated Flow ◽  
Rainfall Infiltration ◽  
Combination Method ◽  
Matrix System ◽  
Capillary Barrier ◽  
Hydraulic Behaviour ◽  
Experimental Apparatus ◽  
Matrix Interactions ◽  
The Matrix ◽  
Flow Through

In this study, an experimental apparatus was developed to investigate unsaturated infiltration in an analog fracture-matrix system. Fracture and adjacent matrix is simulated by sands with various particle sizes. Four rainfall infiltration experiments were performed on the analog fracture-matrix system at a constant rainfall rate of 100 mm/h. The process of rainfall infiltration is measured by a combination method of tensiometers and quick moisture apparatus. The measured results reveal that fracture-matrix interactions certainly exert influences on the hydraulic behaviour of unsaturated fractured matrix, and the fluid flow mainly infiltrates along the nonuniform paths within the matrix. Moreover, it is observed that the influences are greater when using a coarser sand to mimic the fracture. Specifically, the wetting phase in the matrix moves faster than that in the fracture; the fracture, therefore, acts as a vertical capillary barrier, but there exists lateral water exchange from the matrix to the fracture. Overall, this study has demonstrated the importance of fracture/matrix interactions, which should be considered when dealing with unsaturated flow through permeable matrices.

Modeling the Matrix of Articular Cartilage Using a Continuous Fiber Angular Distribution Predicts Many Observed Phenomena

2009 ◽  
Author(s):  
Gerard A. Ateshian ◽  
Vikram Rajan ◽  
Nadeen O. Chahine ◽  
Clare Canal Guterl ◽  
Clark T. Hung
Keyword(s):  
Angular Distribution ◽  
Mechanical Response ◽  
Strain Curve ◽  
Collagen Matrix ◽  
Compressive Properties ◽  
Continuous Fiber ◽  
Stress Strain Curve ◽  
Theoretical Frameworks ◽  
The Matrix ◽  
Discrete Fiber

A number of theoretical frameworks embodying the disparity between tensile and compressive properties of cartilage have been proposed, accounting for the collagen fibers implicitly [1,2] or explicitly [3–5]. These models generally propose discrete fiber families to describe the collagen matrix. They are able to capture the most salient features of the cartilage mechanical response, namely, the tension-compression nonlinearity of the stress-strain curve [6].

Abstract 2876: Early Retention and Subsequent Engraftment of Transplanted Progenitor Cells is Improved by Delivery within Collagen Matrix

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Yan Zhang ◽  
Marc Lamoureux ◽  
Stephanie Thorn ◽  
Vincent Chan ◽  
Joel Price ◽  
...  
Keyword(s):  
Cell Therapy ◽  
Progenitor Cells ◽  
Pet Imaging ◽  
Ex Vivo ◽  
Collagen Matrix ◽  
Cell Labeling ◽  
Type I ◽  
The Matrix ◽  
Early Retention

Background: To investigate the mechanisms involved in the potentiation of cell therapy by delivery matrices, we evaluated the retention and engraftment of transplanted human circulating progenitor cells (CPCs) injected in a collagen matrix by using in vivo positron emission tomography (PET) imaging, ex vivo biodistribution, and immunohistochemistry. Methods: CPCs were labeled with 18 F-FDG and injected with or without a collagen type I-based matrix in the ischemic hindlimb muscle (IM) of rats (2x10 6 cells; n=15/group). Localization of cells was acquired by PET imaging (15 min) at 150 min post-injection. In addition, radionuclide biodistribution, immunofluorescence, and immunohistochemical examination of transplanted CPCs were performed at up to 14 days. Results: Cell labeling efficiency was CPC-concentration dependent (r=0.61, p <0.001), but not 18 F-FDG-dose dependent. Labeled CPCs exhibited excellent short-term stability and viability. Persistence of 18 F-FDG radioactivity in cells was markedly greater than non-specific retention in the matrix. Wholebody (WB) PET images revealed better CPC retention in the IM and less non-specific leakage to other tissues when CPCs were delivered within the matrix (IM/WB retention ratio of 43.9±8.2%), compared to cells injected alone (22.3±10.4%; p =0.040) and to 18 F-FDG injected with or without the matrix (9.7±5.5% and 11.0±5.5%, respectively; p <0.005). Radioactivity biodistribution confirmed that accumulation was increased (by 92.5%; p =0.024) in the IM and reduced (by 1.1 to 23.8%; p <0.05) in non-specific tissues when cells were injected within the matrix, compared to cells injected alone. Anti-human mitochondria staining showed increased cell retention in the IM with use of matrices (3.0±2.1%) versus cells only (1.9±0.8%; p =0.048). At 14 days the number of CD31 + transplanted human cells was greater (1.6±0.1%) when injected within the matrix than injected alone (0.7±0.1%; p =0.004). Conclusions: Collagen-based delivery matrices improve the early retention of transplanted CPCs, which in turn favors subsequent cell engraftment in the ischemic tissue. This mechanism conferred by the matrix has potential implications for the optimization of cell therapy at the early stages after cell delivery.

Preparation and In Vitro Evaluation of Electrochemically-Aligned Collagen Matrix as a Dermal Substitute

MRS Advances ◽  
2016 ◽  
Vol 1 (18) ◽  
pp. 1295-1300 ◽  
Author(s):  
XingGuo Cheng ◽  
Nicole Edwards ◽  
Kelly Leung ◽  
David Zhang ◽  
Robert J. Christy
Keyword(s):  
Transmission Rate ◽  
Collagen Matrix ◽  
Electrochemical Process ◽  
Dermal Substitute ◽  
Adipose Derived Stem Cells ◽  
The Matrix ◽  
Moisture Vapor ◽  
Near Future

ABSTRACTDue to injuries and disease, there is a great need for a robust, biocompatible, biodegradable, skin-like dermal substitute to repair and regenerate damaged or lost skin. A novel electrochemical process was used to fabricate planarly aligned, densely packed collagen-based sheet which closely mimics the major structure of collagen in skin. The collagen matrix was characterized by scanning electron microscopy (SEM), oxygen permeation, moisture vapor transmission rate (MVTR), and mechanical strength. The seeding and proliferation of adipose derived stem cells (ADSCs) on the matrix was also evaluated. The results indicate that electrochemically-aligned collagen matrix has good MVTR, superior oxygen permeability, and is robust and biocompatible. Thus, it will be evaluated in vivo in the near future as a dermal substitute material.

scholarly journals Circumferential Esophageal Replacement by a Tissue-engineered Substitute Using Mesenchymal Stem Cells

2017 ◽  
Vol 26 (12) ◽  
pp. 1831-1839 ◽  
Author(s):  
Jonathan Catry ◽  
Minh Luong-Nguyen ◽  
Lousineh Arakelian ◽  
Tigran Poghosyan ◽  
Patrick Bruneval ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Cell Tracking ◽  
Primary Outcome ◽  
Postoperative Morbidity ◽  
Esophageal Replacement ◽  
Control Group ◽  
Acellular Matrix ◽  
Graft Area ◽  
Cell Colonization

Tissue engineering appears promising as an alternative technique for esophageal replacement. Mesenchymal stem cells (MSCs) could be of interest for esophageal regeneration. Evaluation of the ability of an acellular matrix seeded with autologous MSCs to promote tissue remodeling toward an esophageal phenotype after circumferential replacement of the esophagus in a mini pig model. A 3 cm long circumferential replacement of the abdominal esophagus was performed with an MSC-seeded matrix (MSC group, n = 10) versus a matrix alone (control group, n = 10), which has previously been matured into the great omentum. The graft area was covered with an esophageal removable stent. A comparative histological analysis of the graft area after animals were euthanized sequentially is the primary outcome of the study. Histological findings after maturation, overall animal survival, and postoperative morbidity were also compared between groups. At postoperative day 45 (POD 45), a mature squamous epithelium covering the entire surface of the graft area was observed in all the MSC group specimens but in none of the control group before POD 95. Starting at POD 45, desmin positive cells were seen in the graft area in the MSC group but never in the control group. There were no differences between groups in the incidence of surgical complications and postoperative death. In this model, MSCs accelerate the mature re-epitheliazation and early initiation of muscle cell colonization. Further studies will focus on the use of cell tracking tools in order to analyze the becoming of these cells and the mechanisms involved in this tissue regeneration.

A Model for Ligament Fibroblast Migration Into Provisional Matrix

2011 ◽  
Author(s):  
Yu-Chen Cheng ◽  
Pen-Hsiu Grace Chao
Keyword(s):  
Electric Fields ◽  
Primary Repair ◽  
Cruciate Ligament ◽  
Matrix Material ◽  
Collagen Matrix ◽  
Cell Infiltration ◽  
Gene Expressions ◽  
Knee Ligament ◽  
Fibroblast Migration ◽  
The Matrix

Many strategies have been proposed to enhance the healing capability of the anterior cruciate ligament (ACL). A novel treatment option, called enhanced primary repair, places a provisional matrix at the tear site to promote cell infiltration of the wound and aims to reestablish the structure-function relationship of the ACL [1]. This approach of guided tissue regeneration offers great potential benefits of retaining the complex native tissue matrix structure, innervation, and vascularization as compared with grafts. A major aspect of this procedure is enhancing ligament fibroblast infiltration into the matrix material and promoting matrix synthesis. We have previously demonstrated that applied electric fields (EFs) enhance knee ligament fibroblast migration, alignment, and collagen gene expressions on planar substrates [2]. In the current study, we developed a new system to simulate cell infiltration from the tissue to a provisional collagen matrix. An EF was applied across the construct to investigate its effects of on ACL fibroblast migration into the provisional matrix.

Biomechanical and Optical Characteristics of a Corneal Stromal Equivalent1

2003 ◽  
Vol 125 (4) ◽  
pp. 439-444 ◽  
Author(s):  
Elizabeth J. Orwin ◽  
Melinda L. Borene ◽  
Allison Hubel
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Actin ◽  
Collagen Matrix ◽  
Matrix Composition ◽  
Cell Phenotype ◽  
Matrix Remodeling ◽  
Muscle Actin ◽  
Stromal Fibroblasts ◽  
The Matrix ◽  
Actin Expression

Cell matrix interactions are important in understanding the healing characteristics of the cornea after refractive surgery or transplantation. The purpose of this study was to characterize in more detail the evolution of biomechanical and optical properties of a stromal equivalent (stromal fibroblasts cultured in a collagen matrix). Human corneal stromal fibroblasts were cultured in a collagen matrix. Compaction and modulus were determined for the stromal equivalent as a function of time in culture and matrix composition. The corneal stromal fibroblasts were stained for α-smooth muscle actin expression as an indicator of myofibroblast phenotype. The nominal modulus of the collagen matrix was 364±41 Pa initial and decreased initially with time in culture and then slowly increased to 177±75 Pa after 21 days. The addition of chondroitin sulfate decreased the contraction of the matrix and enhanced its transparency. Cell phenotype studies showed dynamic changes in the expression of α-smooth muscle actin with time in culture. These results indicate that the contractile behavior of corneal stromal cells can be influenced by both matrix composition and time in culture. Changes in contractile phenotype after completion of the contraction process also indicate that significant cellular changes persist beyond the initial matrix-remodeling phase.

The Nature of Covalent Complexes of Phosphoproteins with Collagen in the Bovine Dentin Matrix

1979 ◽  
Vol 58 (6) ◽  
pp. 1625-1633 ◽  
Author(s):  
Jean Curley-Joseph ◽  
Arthur Veis
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Principal Component ◽  
Collagen Matrix ◽  
Covalent Modification ◽  
Mineralization Process ◽  
Collagen Peptide ◽  
Diethylaminoethyl Cellulose ◽  
The Matrix ◽  
Dentin Matrix ◽  
Specific Section

The bovine dentin matrix still contains some non-collagenous proteins after thorough extraction and decalcification. These have been obtained following digestion of the matrix by cyanogen bromide. Peptides containing non-collagenous portions were isolated by chromatography on diethylaminoethyl cellulose columns and fractionated on hydroxyapatite columns. Several fractions were obtained. The principal component was a complex between a highly-phosphorylated serine-aspartic acid-rich protein and a collagen peptide. These collagenous and non-collagenous moieties could not be separated from each other even under highly dissociative solvent conditions. After digestion with collagenase, the resulting phosphoprotein fraction still contained a few residues of hydroxyproline and hydroxylysine, and an enhanced content of pro-line, compared to the equivalent directly extractable phosphophoryn of the matrix. These data were interpreted as indicating that the phosphophoryn which is not extractable in 0.5M ethylenediaminetetraacetic acid is in fact covalently bound to some specific section of the matrix collagen. The covalent modification of the collagen matrix with highly acidic phosphoproteins may have an important role in the mineralization process.

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