Exposure of zebra mussels to extracorporeal shock waves demonstrates formation of new mineralized tissue inside and outside the focus zone

Katharina Sternecker; Juergen Geist; Sebastian Beggel; Kristin Dietz-Laursonn; Matias de la Fuente; Hans-Georg Frank; John P Furia; Stefan Milz; Christoph Schmitz

doi:10.1242/bio.033258

Exposure of zebra mussels to extracorporeal shock waves demonstrates formation of new mineralized tissue inside and outside the focus zone

Biol Open. 2018 Jul 2;7(7):bio033258. doi: 10.1242/bio.033258.

Authors

Katharina Sternecker¹, Juergen Geist², Sebastian Beggel², Kristin Dietz-Laursonn³, Matias de la Fuente³, Hans-Georg Frank¹, John P Furia⁴, Stefan Milz¹, Christoph Schmitz⁵

Affiliations

¹ Extracorporeal Shock Wave Research Unit, Chair of Neuroanatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, 80336 Munich, Germany.
² Aquatic System Biology Unit, Department of Ecology and Ecosystem Management, Technical University of Munich, 85354 Freising, Germany.
³ Chair of Medical Engineering, RWTH Aachen University, 52074 Aachen, Germany.
⁴ SUN Orthopaedics and Sports Medicine, Division of Evangelical Community Hospital, Lewisburg, PA 17837, USA.
⁵ Extracorporeal Shock Wave Research Unit, Chair of Neuroanatomy, Institute of Anatomy, Faculty of Medicine, LMU Munich, 80336 Munich, Germany christoph_schmitz@med.uni-muenchen.de.

Abstract

The success rate of extracorporeal shock wave therapy (ESWT) for fracture nonunions in human medicine (i.e. radiographic union at 6 months after ESWT) is only approximately 75%. Detailed knowledge regarding the underlying mechanisms that induce bio-calcification after ESWT is limited. We analyzed the biological response within mineralized tissue of a new invertebrate model organism, the zebra mussel Dreissena polymorpha, after exposure with extracorporeal shock waves (ESWs). Mussels were exposed to ESWs with positive energy density of 0.4 mJ/mm² (A) or were sham exposed (B). Detection of newly calcified tissue was performed by exposing the mussels to fluorescent markers. Two weeks later, the A-mussels showed a higher mean fluorescence signal intensity within the shell zone than the B-mussels (P<0.05). Acoustic measurements revealed that the increased mean fluorescence signal intensity within the shell of the A-mussels was independent of the size and position of the focal point of the ESWs. These data demonstrate that induction of bio-calcification after ESWT may not be restricted to the region of direct energy transfer of ESWs into calcified tissue. The results of the present study are of relevance for better understanding of the molecular and cellular mechanisms that induce formation of new mineralized tissue after ESWT.

Keywords: Biocalcification; Calcein; Dreissena polymorpha; ESWT; Extracorporeal shock wave therapy; Mineralization model; Xylenol Orange.