An overview of tissue and whole organ decellularization processes.

Fibroblasts can condense a hydrated collagen lattice to a tissue-like structure 1/28th the area of the starting gel in 24 hr. The rate of the process can be regulated by varying the protein content of the lattice, the cell number, or the con- centration of an inhibitor such as Colcemid. Fibroblasts of high population doubling level propagated in vitro, which have left the cell cycle, can carry out the contraction at least as efficiently as cycling cells. The potential uses of the system as an immu- nologically tolerated "tissue" for wound hea ing and as a model for studying fibroblast function are discussed.

Production of a tissue-like structure by contraction of collagen lattices by human fibroblasts of different proliferative

Theory of electroporation: A review

Fluorometric assay of DNA in cartilage explants using Hoechst 33258.

ContextThe efficient sequestration of hemoglobin by the red blood cell membrane
and the presence of multiple hemoglobin clearance mechanisms suggest a critical
need to prevent the buildup of this molecule in the plasma. A growing list
of clinical manifestations attributed to hemoglobin release in a variety of
acquired and iatrogenic hemolytic disorders suggests that hemolysis and hemoglobinemia
should be considered as a novel mechanism of human disease.Evidence AcquisitionPertinent scientific literature databases and references were searched
through October 2004 using terms that encompassed various aspects of hemolysis,
hemoglobin preparations, clinical symptoms associated with plasma hemoglobin,
nitric oxide in hemolysis, anemia, pulmonary hypertension, paroxysmal nocturnal
hemoglobinuria, and sickle-cell disease.Evidence SynthesisHemoglobin is released into the plasma from the erythrocyte during intravascular
hemolysis in hereditary, acquired, and iatrogenic hemolytic conditions. When
the capacity of protective hemoglobin-scavenging mechanisms has been saturated,
levels of cell-free hemoglobin increase in the plasma, resulting in the consumption
of nitric oxide and clinical sequelae. Nitric oxide plays a major role in
vascular homeostasis and has been shown to be a critical regulator of basal
and stress-mediated smooth muscle relaxation and vasomotor tone, endothelial
adhesion molecule expression, and platelet activation and aggregation. Thus,
clinical consequences of excessive cell-free plasma hemoglobin levels during
intravascular hemolysis or the administration of hemoglobin preparations include
dystonias involving the gastrointestinal, cardiovascular, pulmonary, and urogenital
systems, as well as clotting disorders. Many of the clinical sequelae of intravascular
hemolysis in a prototypic hemolytic disease, paroxysmal nocturnal hemoglobinuria,
are readily explained by hemoglobin-mediated nitric oxide scavenging.ConclusionA growing body of evidence supports the existence of a novel mechanism
of human disease, namely, hemolysis-associated smooth muscle dystonia, vasculopathy,
and endothelial dysfunction.

https://jamanetwork.com/journals/jama/articlepdf/200611/JCR50001.pdf

The clinical sequelae of intravascular hemolysis and extracellular plasma hemoglobin: a novel mechanism of human disease.

Mechanical and physicochemical determinants of the chondrocyte biosynthetic response

Victims of major electrical trauma frequently suffer extensive skeletal muscle and nerve damage, which is postulated to be principally mediated by electroporation and/or thermally driven cell membrane permeabilization. We have investigated the efficacy of two blood-compatible chemical surfactants for sealing electroporated muscle membranes. In studies using cultured skeletal muscle cells, poloxamer 188 (P188; an 8.4-kDa nonionic surfactant) blocks, and neutral dextran (10.1 kDa) substantially retards, carboxyfluorescein release from electropermeabilized cell membranes. To test whether P188 administered intravenously could have the same therapeutic effect in vivo, the rat biceps femoris muscle flap attached by its arteriovenous pedicle was electropermeabilized until its electrical resistivity dropped to 50% of the initial value. P188 (460 mg/kg) administered intravenously 20 min postshock restored the resistivity to 77% of the initial value. When P188 was administered intravenously 5 min before shock, a dose-dependent impedance recovery rate was observed. Neither neutral dextran (460 mg/kg) nor sterile saline was effective. Histopathologic studies indicated that postshock poloxamer administration reduced tissue inflammation and damage in comparison with dextran-treated or control tissues. Electrophysiologic evidence of membrane damage was not observed in flaps of animals pretreated with poloxamer. These results suggest that it may be possible to seal in vivo tissue membranes injured by electrical, thermal, or other membrane-damaging forces.

Surfactant-induced sealing of electropermeabilized skeletal muscle membranes in vivo.

Electrical shock trauma tends to produce a very complex pattern of injury, mainly because of the multiple modes of frequency-dependent tissue-field interactions. Historically, Joule heating was thought to be the only cause of electrical injuries to tissue by commercial-frequency electrical shocks. In the last 15 years, biomedical engineering research has improved the understanding of the underlying biophysical injury mechanisms. Besides thermal burns secondary to Joule heating, permeabilization of cell membranes and direct electroconformational denaturation of macromolecules such as proteins have also been identified as tissue-damage mechanisms. This review summarizes the physics of tissue injury caused by contact with commercial-frequency power lines, as well as exposure to lightning and radio frequency (RF), microwave, and ionizing radiation. In addition, we describe the anatomic patterns of the resultant tissue injury from these modes of electromagnetic exposures.

Biophysical Injury Mechanisms in Electrical Shock Trauma

We have measured the dynamics of extracellular matrix consolidation and strengthening by human dermal fibroblasts in hydrated collagen gels Constraining matrix consolidation between two porous polyethylene posts held rigidly apart set up the mechanical stress which led to the formation of uniaxially oriented fibroblast-populated collagen matrices with a histology resembling a ligament We measured the mechanical stiffness and tensile strength of these ligament equivalents (LEs) as a function of age at biweekly intervals up to 12 weeks in culture using a mechanical spectrometer customized for performing experiments under physiologic conditions The LE load-strain curve changed as a function of LE age, increasing in stiffness and exhibiting less plastic-like behavior At 12 weeks, LEs had acquired up to 30 times the breaking strength of 1-week-old LEs Matrix strengthening occurred primarily through the formation of BAPN-sensitive, lysyl oxidase catalyzed crosslinks Sulfated glycosaminoglycan (GAG) content increased monotonically with LE age, reaching levels that are characteristic of ligaments Cells in the LEs actively incorporated [3H]proline and [35S]sulfate into the extracellular matrix Over the first three weeks, DNA content increased rapidly but thereafter remained constant This data represent the first documentation of strengthening kinetics for cell-assembled biopolymer gels and the results suggest that this LE tissue may be a valuable model for studying the cellular processes responsible for tissue growth, repair, and remodeling

Mechanisms and dynamics of mechanical strengthening in ligament-equivalent fibroblast-populated collagen matrices

Electric fields are capable of damaging cells through both thermal and nonthermal mechanisms. While joule heating is generally recognized to mediate tissue injury in electrical trauma, the possible role of electrical breakdown of cell membranes has not been thoroughly considered. Evidence is presented suggestive that in many instances of electrical trauma the local electrical field is of sufficient magnitude to cause electrical breakdown of cell membranes and cell lysis. In theory, large cells such as muscle and nerve cells are more vulnerable to electrical breakdown. To illustrate the significance of cell size and orientation, a geometrically simple model of an elongated cell is analyzed.

Raphael C. Lee

Papers

Mechanical and physicochemical determinants of the chondrocyte biosynthetic response

Surfactant-induced sealing of electropermeabilized skeletal muscle membranes in vivo.

Biophysical Injury Mechanisms in Electrical Shock Trauma

Mechanisms and dynamics of mechanical strengthening in ligament-equivalent fibroblast-populated collagen matrices

Electrical injury mechanisms: electrical breakdown of cell membranes