Charakterisierung von humanen mesenchymalen Stammzellen und Zellen der osteoblastären Differenzierungskaskade

Mit zunehmendem Wissen über die Komplexität der Osteogenese wurde die Aussagekraft einzelner osteoblasten-assoziierter Marker in den letzten Jahren immer mehr in Frage gestellt. Denn der Nachweis einzelner Marker erlaubt weder eine eindeutige Identifikation undifferenzierter hMSC noch eine Abgrenzung von hMSC zu anderen Reifungsstufen der osteoblastären Kaskade. Das Ziel dieser Untersuchung war es daher, über die Erstellung eines immunzytochemischen Färbeprofils mehrerer Marker gleichzeitig, undifferenzierte hMSC eindeutig zu identifizieren und sie gegenüber hOB und evtl. weiteren Differenzierungsstufen der osteoblastären Kaskade abzugrenzen. Durch die Erstellung eines immunzytochemischen Färbeprofils ist es möglich, heterogene Zellpopulationen auf Einzelzellniveau zu charakterisieren und sie voneinander zu unterscheiden. Diese Untersuchung stellt einen sehr erfolgversprechenden Ansatz dar, undifferenzierte humane mesenchymale Stammzellen (hMSC) zu identifizieren und sie von Zellen der osteoblastären Differenzierungskaskade sowie anderen Zelltypen abgrenzen zu können. Insgesamt konnte in dieser Arbeit gezeigt werden, dass humane MSC und humane Osteoblasten jeweils spezifische Färbeprofile aufweisen, die eine eindeutige Diskriminierung der beiden Zellpopulationen erlauben. Für eine spezifische Unterscheidung auf Einzelzellnineau ist eine intensive Suche nach spezifischen Markern oder die Kombination mehrerer Marker notwendig. Von den in dieser Arbeit ausgewählten Proteinen ergaben Bone Sialoprotein, Osteocalcin, Decorin sowie Kollagen-IV und Kollagen-X unterschiedliche Färbemuster. Kollagen-IV und –X waren besonders in hMSC positiv, weswegen sie sich für eine Erkennung unreifer osteoblastärer Zellen anbieten. Bone Sialoprotein, Osteocalcin und Decorin eignen sich dagegen für einen Nachweis reifer osteoblastärer Zellen, denn sie waren nur in hOB positiv. Osteocalcin und Decorin erlaubten außerdem eine Abgrenzung differenzierter hOB. Die Proteine Versican und Matrixmetalloproteinase-2 erscheinen darüber hinaus für eine Unterscheidung von osteoblastären und fibroblastären Zellen nützlich zu sein. Die klassischen osteoblastären Marker alkalische Phosphatase, Kollagen-I, Osteopontin oder Osteonectin waren für eine Unterscheidung von hMSC und hOB nicht geeignet, da sie in beiden Zellpopulationen gleiche Ergebnisse lieferten. Insbesondere der Wert der alkalische Phosphatase als immunzytochemischer Marker der osteoblastären Kaskade wird in dieser Untersuchung in Frage gestellt. Eine osteogene Stimulation von hMSC mit Dexamethason, b-Glyzerophosphat und Askorbinsäure bewirkte eine deutliche Veränderung der Morphologie, der Wachstumseigenschaften und des Färbeprofils. Allerdings konnte durch eine osteogene Stimulation kein immunzytochemischer Phänotyp von hMSC induziert werden, welcher identisch mit dem der hOB war. Daher ist es unwahrscheinlich, dass eine Stimulation in vitro mit den oben aufgeführten Zusätzen die komplizierten Verhältnisse der Osteogenese in vivo nachahmen kann

A dental myth bites the dust - no observable relation between the incidence of dental abscess and the weather and lunar phase: an ecological study

Background: Anecdotal reports assert a relationship between weather and lunar activity and the odontogenic abscess (OA) incidence, but this relationship has not been validated. Therefore, the present study investigated the relationship between oral pain caused by OA and a variety of meteorological parameters and cyclic lunar activity. Methods: The records of all dental emergency patients treated at the AllDent Zahnzentrum Emergency Unit in Munich, Germany during 2012 were retrospectively reviewed. Patients with oral pain who were diagnosed with OA and treated surgically (n = 1211) were included in the analysis. The OA incidence was correlated to daily meteorological data, biosynoptic weather analysis, and cyclic lunar activity. Results: There was no seasonal variation in the OA incidence. None of the meteorological parameters, lunar phase, or biosynoptic weather class were significantly correlated with the OA incidence, except the mean barometric pressure, which was weakly correlated (rho = -0.204). The OA incidence showed a decreasing trend as barometric pressure increased (p < 0.001). On multiple linear regression, the barometric pressure accounted for approximately 4% of the OA incidence. Conclusion: There is no evidence supporting a correlation between the incidence of odontogenic abscess and the weather and lunar activities

Incidence and Risk Factors of Bisphosphonate-Related Osteonecrosis of the Jaw in Multiple Myeloma Patients Having Undergone Autologous Stem Cell Transplantation

Background: Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a severe complication of bisphosphonate therapy. Due to their long survival and subsequently high cumulative doses of bisphosphonates, multiple myeloma patients have the highest risk of developing BRONJ of all patients treated with bisphosphonates. The purpose of the present study was to evaluate the incidence and risk factors for BRONJ in multiple myeloma patients after high-dose chemotherapy and autologous stem cell transplantation (ASCT). Patients and Methods: We retrospectively analyzed the data of 120 multiple myeloma patients after high-dose chemotherapy and ASCT treated with bisphosphonates and assessed the incidence and risk factors of BRONJ. Results: Of the 120 patients, 23 (19%) developed BRONJ. 6 patients suffered several BRONJ events, resulting in a total incidence of 23%. The risk for BRONJ was significantly higher for patients with rheumatism and recent dental manipulations. Furthermore, the number of previous bisphosphonate rotations, the duration of bisphosphonate therapy, and the type and cumulative dose of bisphosphonate used were associated with the incidence of BRONJ. Conclusion: Our study is the first to determine the risk of BRONJ in a homogeneous group of multiple myeloma patients treated with high-dose chemotherapy and ASCT

Management von medikamentenassoziierten Kiefernekrosen – Ergebnisse einer Literaturanalyse neuester Studien im Vergleich zu bewährten Strategien

BACKGROUND Antiresorptive agents are some of the most frequently used drugs worldwide, with indications in osteology and oncology. They are generally well tolerated and display a~favorable safety profile. A~potentially severe unwanted side effect is medication-related osteonecrosis of the jaw (MRONJ). PURPOSE OF THIS REVIEW This review summarizes the latest developments in etiology, diagnosis, and treatment of MRONJ, and compares new insights with established algorithms. METHODS A~systematic review of relevant studies exploring diagnostic methods, prospective management trials, and innovative studies on the pathogenesis of MRONJ published between 2016 and 2021 was performed. The study quality was assessed using the MINORS (methodological index for non-randomized studies) rating score. RESULTS AND DISCUSSION The prevalence of MRONJ in patients undergoing treatment with antiresorptive drugs for oncological reasons is remarkable (2-12%). MRONJ prevalence in patients receiving antiresorptive drugs for the treatment of osteoporosis is much lower (0.1-1%). MRONJ treatment should be initiated early and involve a~surgical approach. MRONJ treatment is safe and predictable, with long-term success rates of more than 85%. ZUSAMMENFASSUNG HINTERGRUND: Antiresorptiva gehören weltweit zu den am häufigsten applizierten Arzneimitteln. Ihr Haupteinsatzbereich liegt in der Osteologie und Onkologie. Trotz allgemein guter Verträglichkeit treten bei Patienten unter Therapie unerwünschte Arzneimittelwirkungen (UAW) auf. Eine spezifische UAW im Bereich der Kiefer ist die sog. medikamentenassoziierte Osteonekrose („medication-related osteonecrosis of the jaw“, MRONJ) der Kiefer. ZIEL DER ARBEIT Diese Arbeit stellt neuesten Entwicklungen in Ätiologie, Diagnostik und Therapie der MRONJ im Vergleich zu bereits bestehenden Erkenntnissen zusammen. METHODIK Es wurde eine systematische Literaturübersicht der Jahre 2016–2021 zu diesem Thema durchgeführt. Prospektive Therapiestudien, Diagnostikstudien mit Vergleichsgruppe und innovative Studien zur Pathogenese der MRONJ wurden eingeschlossen und nach den MINORS-Kriterien („methodological index for non-randomized studies“) bewertet. ERGEBNISSE UND DISKUSSION Die MRONJ tritt bei ca.~2–12 % der Patienten, die aus onkologischer Indikation mit Antiresorptiva behandelt werden, auf (osteologische Indikation ca.~0,1–1 %). Die Therapie der MRONJ sollte frühzeitig und operativ erfolgen. Die Heilungsrate ist bei einem operativen Therapieansatz mit über 85 % sehr gut

Risk factors associated with onset of medication-related osteonecrosis of the jaw in patients treated with denosumab

OBJECTIVES While risk factors of bisphosphonate (BP) associated osteonecrosis of the jaw have been properly analyzed, studies focusing on risk factors associated with denosumab (DNO) are sparse. The purpose of this study was to identify risk factors influencing the onset of medication-related osteonecrosis of the jaw (MRONJ) in patients receiving antiresorptive treatment (ART) with DNO by comparing patients suffering from MRONJ and patients without MRONJ. Multiple variables were evaluated including the impact of a previous BP intake. MATERIALS AND METHODS A retrospective single-center cohort study with patients receiving DNO was conducted. One-hundred twenty-eight patients were included and divided into three groups: I (control, n = 40) receiving DNO with absence of MRONJ; group II (Test 1, n = 46), receiving DNO with presence of MRONJ; and group III (Test 2, n = 42) sequentially receiving BP and DNO with presence of MRONJ. Patients' medical history, focusing on the identification of MRONJ risk factors, was collected and evaluated. Parameters were sex, age, smoking habit, alcohol consumption, underlying disease (cancer type, osteoporosis), internal diseases, additional chemo/hormonal therapy, oral inflammation, and trauma. RESULTS The following risk factors were identified to increase MRONJ onset significantly in patients treated with DNO: chemo/hormonal therapy (p = 0.02), DNO dosage (p < 0.01), breast cancer (p = 0.03), intake of corticosteroids (p = 0.04), hypertension (p = 0.02), diabetes mellitus (p = 0.04), periodontal disease (p = 0.03), apical ostitis (p = 0.02), and denture use (p = 0.02). A medication switch did not affect MRONJ development (p = 0.86). CONCLUSIONS Malignant diseases, additional chemotherapy, DNO dosage, and oral inflammations as well as diabetes mellitus and hypertension influence MRONJ onset in patients treated with DNO significantly. CLINICAL RELEVANCE Patients receiving ART with DNO featuring aforementioned risk factors have a higher risk of MRONJ onset. These patients need a sound and regular prophylaxis in order to prevent the onset of MRONJ under DNO treatment

The Alvarez and Lohmann refractive lenses revisited

15 pages, 10 figures.-- OCIS codes: 080.1510, 080.2740, 330.4460.Alvarez and Lohmann lenses are variable focus optical devices based on lateral shifts of two lenses with cubic-type surfaces. I analyzed the optical performance of these types of lenses computing the first order optical properties (applying wavefront refraction and propagation) without the restriction of the thin lens approximation, and the spot diagram using a ray tracing algorithm. I proposed an analytic and numerical method to select the most optimum coefficients and the specific configuration of these lenses. The results show that Lohmann composite lens is slightly superior to Alvarez one because the overall thickness and optical aberrations are smaller.I benefit from a Spanish Ministry of Science-UPM "Ramón y Cajal" contract.Peer reviewe

Osteonecrosis of the jaw as a possible rare side effect of annual bisphosphonate administration for osteoporosis: A case report

<p>Abstract</p> <p>Introduction</p> <p>Osteonecrosis of the jaw is a serious side effect in patients receiving nitrogen-containing bisphosphonates intravenously due to malignant diseases. Albeit far less frequently, osteonecrosis of the jaw has also been reported to occur due to the oral administration of nitrogen-containing bisphosphonates due to osteoporosis. Annual infusions of zoledronic acid have been recommended in order to improve patient compliance, to optimize therapeutic effects and to minimize side effects. To date, osteonecrosis of the jaw has not been linked to the annual administration of bisphosphonates.</p> <p>Case presentation</p> <p>We report the case of a 65-year-old Caucasian woman suffering from osteoporosis who developed early stage osteonecrosis of the jaw in two locations, with chronic infections, after two months of oral bisphosphonate treatment and three annual administrations of zoledronic acid. Our patient was treated by fluorescence-guided resection of the necrotic jaw bone areas; local inflammation was treated by removal of a wisdom tooth and repeat root resections. Histopathology revealed typical hallmarks of osteonecrosis of the jaw.</p> <p>Conclusion</p> <p>Osteonecrosis of the jaw may occur as a consequence of annual administrations of zoledronic acid. It is conceivable that, due to the pharmacological properties of bisphosphonates, a jaw bone that encounters frequent local inflammations is more likely to develop osteonecrosis.</p

The use of four-colour immunofluorescence techniques to identify mesenchymal stem cells

In stem-cell research a major difficulty is caused by the lack of distinctive features that allow the identification of human mesenchymal stem cells (hMSC). Until now, there has been no specific marker and the most common way to identify hMSC is by their characteristic stem-cell properties: self-replication and differentiation potential. However, these findings can only be revealed retrospectively, and, once differentiated, hMSC lose their stem-cell character. The aim of this study was to establish four-colour immunofluorescence of several markers simultaneously in order to address the problem of how to identify hMSC on the single-cell level. The four markers collagen-I, collagen-IV, fibronectin and CD44 are known to be expressed by hMSC. Antibody binding was detected using secondary antibodies conjugated to FITC, Alexa546, TexasRed and AMCA. Because the distinction between Alexa546 and TexasRed was not possible on conventional digital images using standard filter sets, we performed spectral image acquisition. The image was subsequently decomposed into its pure spectral components, which permitted linear unmixing. Using this procedure we were able to demonstrate four-colour immunofluorescence on hMSC. With the possibility of using more sophisticated marker profiles and/or additional markers, four-colour immunofluorescence offers the opportunity of identifying hMSC on the single-cell level without performing differentiation assays