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Reduction and Fixation of Sacroiliac joint Dislocation by the Combined Use of S1 Pedicle Screws and an Iliac Rod
Published in Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White, Advances in Spinal Fusion, 2003
Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White
We have developed a hypothetical model for the role of PRP in bone healing. In summary, we suggest that the local application of PRP causes migration of MSCs to the wound site, followed by their replication to form a repair blastema. As the bioactive factors diffuse away from the fibrin scaffold, now densely populated by MSCs, the cells cease dividing and are primed to respond to the endogenous inductive cues that stimulate differentiation phase. The local and transient activity of PRP in this model of tissue repair is responsible for initiating and accelerating the natural healing cascade and thus increasing the rate of bone fusion. Osteoprogenitor Cells as a Therapeutic Bone Graft Material
Clinical Relevance of t-PA Levels and of Fibrinolytic Assays
Published in Cornelis Kluft, Tissue-Type Plasminogen Activator (t-PA): Physiological and Clinical Aspects, 1988
From a theoretical point of view it might be conjectured that a too-active fibrinolysis will cause precocious removal of fibrin from a fresh wound and oppose hemostasis. In this case one would expect rebleeding of middle-sized and larger wounds to occur after a delay of a couple of hours or a day or so, when the fibrin scaffold of the hemostatic plug collapses. The hemostasis of pinpricks and the like depend largely on platelets. Nevertheless, streptokinase influences the bleeding time of small puncture wounds in rabbit mesentery as demonstrated by Hirsh et al.20 There is convincing clinical evidence that unrestrained fibrinolysis does cause bleeding. In the patient with congenital α2-antiplasmin deficiency described by us,21 the only detectable abnormality was a lack of this plasmin inhibitor; in contrast to cases described by others,22,23 the t-PA activity was normal. The hemorrhagic tendency could thus safely be attributed to the mere absence of antiplasmin. Plasmin will be formed at a normal rate at sites where fibrinolysis plays its usual role; when not tempered by antiplasmin, this enzyme will digest strategically important fibrin structures, and hemorrhage ensues. In the presence of normal levels of inhibitors, conversion of plasminogen to plasmin will not result in premature removal of fibrin, and the wound will remain sealed and is allowed to heal in due time.
Adult Stem Cells for Intervertebral Disc Repair
Published in Raquel M. Gonçalves, Mário Adolfo Barbosa, Gene and Cell Delivery for Intervertebral Disc Degeneration, 2018
Esther Potier, Delphine Logeart-Avramoglou
One of the major stumbling blocks in cell-based therapies for IVD repair, however, is the cell delivery protocol into the NP structure, which commonly relies on a trans-annular puncture. Since AF has a limited healing potential, most of the proposed therapies may actually initiate or worsen IVD degeneration. AF puncture is, after all, one of the validated methods used to induce IVD degeneration in animal models. Consistency of degeneration initiation, however, appears to be related to needle size, with larger ones resulting in a greater degeneration (Elliott et al. 2008; Hsieh et al. 2009; Keorochana et al. 2010). Similar observations have been noticed in asymptomatic patients submitted to discograms: over a 10-year period, greater IVD degeneration was observed in patients who had discograms with a 22-G needle compared with those who had discograms with a 25-G needle (Carragee et al. 2009). Although small needle size can be used to minimize the incidence of IVD degeneration after AF puncture, the risk to potentially harm patients persists and complementary methods should be sought. One option is to capitalize on the homing property of intravenously injected MSCs toward injured tissues (Cornelissen et al. 2015) to bypass a direct cell injection and keep the AF intact. This approach is discussed in Chapter 6. Another option is to repair the AF puncture after cell injection. Attempts to close punctured AF by sutures or annuloplasty devices have shown a tendency to improve, although not significantly, IVD healing after hernia discectomy (Ahlgren et al. 2000; Bailey et al. 2013; Bron et al. 2010). More recently, tissue engineering approaches have also been proposed for repairing damaged AF (for recent reviews, see Guterl et al. 2013 and Sharifi et al. 2015). Interestingly, MSCs, in association with pentosan polysulfate and a gelatin/fibrin scaffold, were used to close damaged AF in a sheep model and to successfully reduce the resulting IVD degeneration (Oehme et al. 2014).
PRP in wound healing applications
Published in Platelets, 2021
In summary, the therapeutic mechanisms of wound healing mediated by PRP are due to the action of platelet-derived growth factors and cytokines, which regulate the immune system and trigger cellular regenerative processes in all tissues. On the other hand, plasma offers a fibrin scaffold for regeneration and controls the proliferative and oxidative homeostasis during wound healing. This knowledge was generated by the relevant contribution made by many researchers who measured the levels of growth factors, cytokines, fibrillar components and cells, and analyzed the functionality of PRP in vitro or in vivo. In future studies, a more holistic vision that considers the impact of endogenous and exogenous factors should be applied to the experimental design and interpretation of the results. This will allow us to understand the true impact that the individual and combined components of PRP have on wound healing. It will contribute to designing a more efficient and personalized therapy and to developing possible new therapeutic applications of regenerative treatments mediated by PRP.
Evidence-based indications of platelet-rich plasma therapy
Published in Expert Review of Hematology, 2021
Shyla Gupta, Anna Paliczak, Diego Delgado
The biological properties of PRP have a vast array of content and purity. PRP regenerative properties are dependent on the release of bioactive proteins after platelet activation. Understanding that the concentration of leukocytes present can have an enormous impact on efficacy is critical. They are vital components in healing and the regulation of growth factor alongside platelet mediators that attracts leukocytes to the site of injury [28]. Additionally, autologous plasma with platelet-derived proteins is implied when PRP therapy is implemented [29]. A fibrin scaffold from this implementation helps to heal injured tissue by acting as a matrix. This scaffold further helps platelets play a fundamental role in thrombosis and hemostasis [30]. Platelets contribute their hemostatic capacity via adhesion, activation, and aggregation, triggered upon tissue injury, and these actions stimulate the coagulation factors and other mediators to achieve hemostasis [8]. These coordinated series of events are the vital biological processes for wound healing phases.
Fibrin gel as a scaffold for photoreceptor cells differentiation from conjunctiva mesenchymal stem cells in retina tissue engineering
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Mostafa Soleimannejad, Somayeh Ebrahimi-Barough, Masoud Soleimani, Samad Nadri, Seyed Mohammad Tavangar, Ramak Roohipoor, Meysam Yazdankhah, Neda Bayat, Mohammad Riazi-Esfahani, Jafar Ai
Scanning electron microscopy (SEM) was used as a tool for investigation of the fibrin scaffold microstructure and cell-seeded fibrin gels. Fibrin gels being freeze-dried in vacuum for 24 h, the scaffold constructs were observed under the SEM then fixed in 2.5% glutaraldehyde, and for SEM, cell-seeded fibrin gels were fixed with 2.5% (w/v)glutaraldehyde for 1 h at room temperature after 6 days in-culture. Thereafter, the samples were washed in phosphate-buffered saline (PBS), and then dehydrated through a graded series in 30%, 50%, 70%, 90%, 95% and 100% ethanol, vacuum dried, mounted onto aluminum stubs, and sputter coated with gold. Samples were examined with scanning electron microscope (KYKY EM-3200; Hitachi, Japan) at an accelerating voltage of 17–25 kV.