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Results for “Tissue regeneration”

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At least 37 records · Page 2Linked to original sources
PubMed1979

Mechanical properties and hydroxyproline content of connective tissue in porous ceramic implants.

The present study describes a model applying ceramic implants (A1203) for in vivo studies of connective tissue regeneration. Two types of implants have been developed: a one-piece model for histological examination and chemical analyses, and a two-piece implant which can also be used for mechanical testing of connective tissue. When these were implanted subcutaneoulsly on the back of rats, a correlation was found between the mechanical strength and the hydroxyproline content of connective tissue in the implants. The peak synthesis occurred between the 7th and the 14th day after implantation, and a plateau was reached for both strength-increases and hydroxyproline-formation between the 14th and the 21st days. For histological examination, the implants were embedded in plastic materials and prepared as hard tissue specimens. The model presented can be applied to study connective tissue regeneration in normal and pathological conditions, including studies of the effects of various drugs on the connective tissue.

Aluminum Oxide↗
PubMed2026

Matrix Metalloprotease 1 (Mmp1) promotes cell fate change for epithelial-to-epithelial transition during regeneration after radiation damage in Drosophila.

Ionizing radiation (IR) is used to treat cancer, but therapeutic failure occurs when surviving cancer cells change fate and regenerate tumors through acquired stem cell-like properties. While transcriptional mechanisms underlying cell fate plasticity have been characterized, the cellular processes enabling cell movement during tissue regeneration remain unclear. We reported previously that hinge cells of the Drosophila larval wing disc convert to pouch fate and translocate to help regenerate the pouch that suffers from more IR-induced apoptosis. We report here that IR increases the expression of extracellular proteins in the hinge, including secreted proteases and cell adhesion modulators. Functional validation using RNA interference revealed that secreted Matrix Metalloprotease 1 (Mmp1) and the related secreted protease homolog Scarface (Scaf) are required in hinge cells for IR-induced cell fate conversion and translocation. IR, we found, induces Mmp1 and scaf transcripts in hinge cells via cell-autonomous JNK signaling. Overexpression of Mmp1 specifically in the hinge was sufficient to elevate Mmp1 protein levels throughout the disc and induced cell fate change of both hinge and non-hinge cells but only in the context of irradiation. Confocal imaging in a time course demonstrated that cells undergoing fate conversion remain within the epithelial layer with little evidence for delamination or epithelial-mesenchymal transition (EMT). We propose that remodeling of the extracellular environment is a critical mechanism that enables cellular reorganization during tissue regeneration. Mmp enzymes are important for cancer biology because of their role in ECM remodeling, extracellular signaling, and EMT. Our findings demonstrate for the first time that Mmp1 is necessary and sufficient for one epithelial cell type to switch to another epithelial cell type after radiation damage. These results provide a mechanistic basis for radiation therapy-induced cell fate plasticity.

Animals↗
PubMed1978

Regulation of interstitial cell differentiation in Hydra attenuata. V. Inability of regenerating head to support nematocyte differentiation.

Nematocyte differentiation was examined during head regeneration in Hydra attenuata. Nematocyte precursors were found to decrease in head-regenerating tissue. This decrease could not be attributed to decreased stem cell commitment or to altered cellular kinetics. The nematocyte precursors could be 'rescued' by regrafting a head onto the initially regenerating tissue only prior to the time at which head determination occurred. These results suggest that concurrent with head determination an irreversible change occurs in the tissue environment, resulting in decreased survival of cells committed to nematocyte differentiation.

Animals↗
PubMed1978

Regeneration of rabbit calcaneal tendon: a morphological and immunochemical study.

The regenerated tissue which fills the gap between the stumps of sectioned and unsutured rabbit calcaneal tendon was studied by immunofluorescence, light and electron microscopy from 2 days to 30 weeks after surgery. In the early stages, the newly formed tissue consisted of few connective tissue cells of variable shape dispersed in an abundant intercellular matrix. At 7 days after tenotomy most of the cells were spindle shaped and arranged along the major tendon axis. They showed a well developed rough endoplasmic reticulum, a prominent Golgi complex and bundles of thin and thick filaments. Moreover, they appeared intensely stained when treated with anti-actin and anti-myosin sera. The bulk of the intercellular matrix consisted of bundles of collagen fibers, mostly arranged parallel to the cells. In the subsequent stages the regenerating tissue became more compact, acquiring the morphological characteristics of tendon tissue. At 30 weeks after tenotomy, however, it did not show yet the typical texture of the normal adult tendon. The tenocytes were more numerous and less uniformly distributed, and contained a greater amount of ergastoplasm and contractile proteins. The collagen fibers were similar in size to those of the neonatal normal tendon and the elastic fibers appeared often immature.

Actins↗
PubMed2026

Microblasting Wound Dressings Mechanically Disrupt Polymicrobial Biofilms to Enhance Healing in Treatment-Resistant Wounds.

Treatment-resistant wounds driven by polymicrobial biofilms are a major clinical challenge, affecting millions globally and leading to chronic inflammation, persistent pain, and poor healing outcomes. These wounds are characterized by mature biofilms reinforced by dense extracellular polymeric substances, which confer strong tolerance to conventional treatments. Despite emerging technologies, such as nanoparticles, bacteriophages, and engineered enzymes, effective clearance of established biofilms remains challenging. Here, we develop a microblasting wound dressing (µBLAST) that delivers spatially confined mechano-chemical disruption at the tissue-biofilm interface to remove viscoelastic biofilm matrices and promote tissue regeneration. The µBLAST is assembled by embedding MnO2-doped diatom biosilica beneath an H2O2-releasing cellulose mesh, enabling localized catalytic microbubble generation within biofilm matrices. Confined expansion and rupture of oxygen bubbles produce localized mechanical stress sufficient to dislodge mature, antibiotic-resistant polymicrobial biofilms, while sustained H2O2 release prolongs particle activity. In a murine wound model infected with mature P. aeruginosa and methicillin-resistant S. aureus biofilms, µBLAST treatment significantly reduces biofilm burden, accelerates re-epithelialization, promotes hair regrowth, and mitigates inflammation. Moreover, µBLAST enhances antibiotic efficacy, suppressing biofilm regrowth even at ten-fold reduced drug doses. These findings highlight confined mechano-chemical biofilm disruption as a therapeutic strategy for treating mature, antibiotic-resistant biofilm infections and promoting tissue regeneration.

Biofilms↗
PubMedDate not supplied

[Effect of carbostimulin and vitamin D3 on activity of glycolytic enzymes of rabbit bones, regenerates and muscles].

Activity of glycolysis enzymes such as: phosphofructokinase, aldolase, phosphoglucomutase, was determined in the regenerate of a bone, bone fragments, native bone and, for the sake of comparison, in the animal muscles after the radius resection and feeding of carbostimulin and its mixture with vitamin D3 for 10 days. On the 12th day after the radius resection the phosphofructokinase activity in rabbits increases in the native and operated bones as compared to that in bones of nonoperative animals. In the group of rabbits which were fed on the mixture of carbostimulin and vitamin D3 the phosphofructokinase activity is 7-2 times as high. In the regenerate of these animals the activity becomes 12 times as high as that in the regenerate of the control rabbits. An analogous increase in the aldolase and phosphoglucomutase reaction rate is observed in the bones of the animals which received carbostimulin and vitamin D3 (4.5 and 7.5 times, respectively). The same tendency to the increase in the activity of these enzymes is observed in the regenerate tissue. In the muscular tissue at this stage of regeneration the activity of the studied enzymes which is usually high in norm decreases.

Animals↗
PubMed1979

[Electron microscopic study of the characteristics of skeletogenic tissue differentiation during distraction osteosynthesis].

Electron microscopic examination of the regenerating tissue was performed after distractional osteosynthesis carried out by the method of G. A. Ilizarov. The results showed osteogenesis to occur on the basis of the fibrous tissue formed in diastasis. The observed zones of the regeneration typical of distractional osteosynthesis are due to functional stimulation (tension) resulting in the arrangement of collagen fiber bundles and bone trabeculae in the direction of the extension forces. Cells of the skeletogenic tissue, between the bone fragments are also arranged with their longitudinal axis along the collagen fibril bundles. The ultrastructural pattern of the osteogenesis after distractional osteosynthesis reflects the intensification of the synthesis of glycosaminoglycan-protein complexes forming the main substance of the bone tissue.

Animals↗
PubMed1978

[Mechanism of the stimulating effect of an electric current on reparative regeneration of bone tissue].

Experiments were conducted on rabbits. Changes in ATP in the regenerating bone tissue after incomplete osteotomy and removal of a bone section, and also in cases of reparative osteogenesis stimulation in the region of the bone defect by means of pulse electric current were studied. ATP content in the bone callus after incomplete osteotomy and electrostimulation proved to exceed such in the regenerating bone tissue following removal of the bone fragment when no stimulation was applied. On the basis of the data obtained it is suggested that improvement of energy provision of the fracture consolidation process was one of the important links in the mechanism of stimulating influence of the electric current on the reparative regeneration of the bone tissue.

Adenosine Triphosphate↗
PubMed2026

Transcriptomic Profiling Reveals NF-κB-Associated Immune Regulatory Signatures Underlying the Regenerative Effects of Hypoxia-Preconditioned Tendon Stem Cell-Derived Extracellular Vesicles.

Remodeling of the immune microenvironment is a critical determinant of tissue regeneration, yet the molecular programs associated with the enhanced therapeutic activity of hypoxia-preconditioned extracellular vesicles remain incompletely defined. In this study, we investigated the regenerative and immunomodulatory effects of hypoxia-preconditioned tendon stem cell-derived extracellular vesicles (Hypo-EVs) and employed transcriptomic profiling to identify molecular signatures associated with their biological activity. The therapeutic effects of Hypo-EVs were evaluated using a rat patellar tendon defect model and lipopolysaccharide-stimulated RAW 264.7 macrophages. Histological analysis, immunostaining, biomechanical testing, and reverse transcription-quantitative polymerase chain reaction were performed to assess tendon healing and macrophage polarization, while RNA sequencing was conducted in macrophages treated with Hypo-EVs or normoxia-derived EVs, followed by Gene Set Enrichment Analysis, Gene Ontology, and Kyoto Encyclopaedia of Genes and Genomes pathway analyses. Hypo-EVs significantly alleviated local inflammatory responses, improved collagen organization and biomechanical properties of repaired tendons, and promoted macrophage polarization toward a reparative M2 phenotype both in vivo and in vitro. Consistent with these biological effects, transcriptomic profiling revealed extensive remodeling of inflammation-related gene expression programs, including significant suppression of NF-κB, TNF, IL-17, and cytokine-cytokine receptor interaction pathways. Integrative bioinformatic analyses identified an NF-κB-associated immune-regulatory signature that distinguished Hypo-EV-treated macrophages from those receiving normoxic EVs. Mechanistically, Hypo-EVs attenuated NF-κB activation, as evidenced by reduced phosphorylation of p65 and IκBα, whereas TNF-α-mediated NF-κB activation partially diminished their macrophage-repolarizing effects. Collectively, these findings demonstrate that hypoxic preconditioning enhances the immunomodulatory and regenerative functions of tendon stem cell-derived EVs. Transcriptomic analyses identified an NF-κB-associated immune-regulatory signature linked to the biological activity of Hypo-EVs, providing a molecular framework for understanding EV-mediated immune modulation and supporting the development of transcriptome-guided molecular signatures for regenerative therapies targeting tendon immune homeostasis.

Animals↗
PubMed1978

[Regeneration of synovial tissue in rheumatoid arthritis following synovectomy (author's transl)].

A study was carried out on 83 knee joints which had been subjected to synovectomy for rheumatoid arthritis. The morphological changes in the synovial tissue were divided into two types, Type I or hypertrophic and Type II or hypotrophic. Type I (hypertrophic) exhibited oedema, hypervascularization, fibrinous layers, large amounts of villi and granulationlike tissue, lymphocytes and plasma cells. Type II (hypotrophic) contained all the above elements, but to a much lesser degree, and fibrosis was the dominant feature. Regenerated synovial tissue was removed one to three years after the original synovectomy by arthrotomy or biopsy in 26 patients who were symptom-free. The tissue was thinner and hardly any villi were seen. The typical inflammatory elements were seen, but were not as pronounced as in the original tissue, irrespective of type. A heavy fibrosis was most frequently seen, but apart from this the regenerated tissue greatly resembled the original.

Arthritis, Rheumatoid↗
PubMed1978

[Contractile connective tissue cells and wound healing. Function of myoid fibroblasts in reparative regeneration of mesenchymal tissue].

The present survey deals with processes of wound healing with special regard to fibroblast proliferation. Comparative experimental studies on reparative and regenerative fibroblastic proliferates and findings from the literature point to the importance of a fibroblast modification with myoid structure in certain phases of the reparative regeneration of the connective tissues. The ultrastructural picture of the myoid fibroblasts and their functional significance are discussed with regard to wound healing in man.

Achilles Tendon↗
PubMed1977

[Regeneration of the myocardium of fetuses and newborn rabbits].

The work is devoted to studies of regeneration of the myocardium in fetuses and newborns of rabbits after a mechanical trauma of the heart. It was established that in fetuses under natural conditions of the alive organism instead of the perished tissue of the myocardium during the period of 5-8 days there developed a wholesome transverse-striated musculature whose fibers contained glycogen and redox enzymes. In newborn rabbits the defect of the myocardium was replaced by a mature fibrous connective tissue, regeneration was accomplished at the expence of hyperplasia of intracellular ultrastructures. The loss by the heart muscular tissue of the capacity for complete regeneration takes place within the 24th day of the intrauterine development and the 1st day of life.

Animals↗
PubMed1977

Formation of after-cataract by regeneration of human and rabbit lens epithelium in tissue culture.

Regeneration of lens epithelium on the lens capsule was studied in tissue culture. The entire capsule with attached epithelium was taken from rabbit lenses and from human lenses with cataract. Generally, the epithelium grew in a monolayer but multilayered masses of cells were also seen. Most lens fibers degenerated during the first days and formed spherical membrane enclosed vesicles containing cytoplasm but no nuclei. The lens fiber remnants, together with regenerating epithelium, created structures that were similar in many ways to the clinical appearance of after-cataract.

Animals↗
PubMed1975

In vivo electron spin resonance in rats.

In vivo ESR studies have been made on Wistar and Sprague-Dawley rats using travelling wave helices implanted in the left lobe of the liver. Tissue regenerates completely around the Teflon-enclosed turns of the coil and histological studies have shown that it is composed of liver cells and connective tissue. Electron spin resonance studies of this tissue in vitro reported by Commoner and Ternberg in 1961 have demonstrated that it exhibits the 'tissue radical' signal. The implanted coils have detected, in vivo, a three-line spectrum due to a strong concentration of 4-hydroxy- 2,2,6,6-tetramethylpiperidine-1-oxyl free radical ('tempol'), a nitroxide spin label, injected either intramuscularly, intraperitoneally or intravenously into the experimental animal immediately prior to the measurement. They have also detected, in vivo, a similar three-line spectrum due to 'spin-labelled chlorpromazine', a tranquillizing drug to which this nitroxide spin label has been attached, injected intramuscularly or intraperitoneally into the animal immediately prior o the measurement. Work is currently in progress to increase the in vivo sensitivity of the implanted helices by menas of improved coupling techniques and the use of a time-averaging computer.

Animals↗
PubMed1977

Regeneration in the central nervous system of a pulmonate mollusc, Melampus.

The left cerebral ganglion was ablated from 72 anesthetized, adult Melampus bidentatus (Mollusca: Pulmonata). Skin incisions were well healed and normal feeding and locomotion observed four days after surgery. Dissections of animals sacrificed weekly showed that most nerves and connectives regrew within 30 days, attaching to the swollen end of the major labial nerve. The enlarged end of this nerve later developed into a distinctive bud; some of these buds contained cell bodies as soon as 42 days after surgery. As the first known report of central nervous tissue regeneration in molluscs, this study points to the need for controls in experiments involving section or ablation of nervous tissue in molluscs.

Animals↗
PubMed1977

Virus-induced lysosomal enzyme dissolution of nasal turbinate cartilage.

The mechanism of laryngotracheitis virus-induced dissolution of chick nasal turbinate cartilage was studied by lysosomal enzyme histochemistry. Five-day-old chicks were infected by intranasal instillation, and changes in lysosomal enzyme distribution were followed at daily intervals through the tissue regeneration stage, Day 28. In the mucosa the lysosomes were activated beginning on Day 1, and glycerol acid phosphatase and a diffuse form of beta-glucuronidase were released concomitant with tissue cell destruction. In the chondrocytes (where glycerol acid phosphatase was absent), beginning on Day 2, particulate (lysosomal) beta-glucuronidase decreased as diffuse beta-glucuronidase increased and extended out into the matrix. The cartilage lost its metachromatic staining properties and became soft and pliable. Regeneration of the mucosa started on Day 6 and gradual reappearance of metachromatic staining of the cartilage began on Day 8 with considerable recovery of original turbinate structure by Day 12. A lysosomal membrane labilizer, vitamin A, exacerbated the cartilage pathology, whereas a stabilizer, cortisone, retarded it.

Acid Phosphatase↗
PubMed1977

A mechanism of tumourigenesis: retrodifferentiation and reontogeny in cancer and its clinical significance.

A general theory for the origin and maintenance of the neoplastic state in tissues is presented. Cancer is described as a disease of abnormal cell and tissue differentiation, and its underlying cause is identified in the process of blocked reontogeny. Data are presented which support this hypothesis and show the striking similarities at the molecular level between neoplastic, embryonic and regenerating tissues. The hypothesis suggests that numerous potentially useful (in the clinical sense) proteins, all of them members of early development, may be associated with neoplasms. It is suggested that research aimed at extending the identification and measurement of these proteins will make a significant contribution to the clinical management of cancer and may lead to the development of easy and cheap screening techniques for the early diagnosis of neoplastic disease in man.

Alkaline Phosphatase↗