Development of Methods to Investigate Pulmonary Arterial Smooth Muscle Cells under Hypoxia

Document identifier: oai:DiVA.org:ltu-77140
Keyword: Engineering and Technology, Medical Engineering, Teknik och teknologier, Medicinteknik, Mechanical Engineering, Applied Mechanics, Maskinteknik, Teknisk mekanik, Experimentell mekanik, Experimental Mechanics
Publication year: 2019
Relevant Sustainable Development Goals (SDGs):
SDG 3 Good health and wellbeing
The SDG label(s) above have been assigned by OSDG.ai

Abstract:

Hypoxic pulmonary vasoconstriction (HPV) is a physiological response to localized alveolarhypoxia that is intrinsic to the pulmonary circulation. By hypoxia-induced contractionof pulmonary arterial smooth muscle cells (PASMCs), the pulmonary capillary bloodflow is redirected to alveolar areas of high oxygen partial pressure, thus maintaining theventilation-perfusion ratio. Although the principle of HPV was recognized decades agothe underlying pathway remains elusive. The patch clamp technique, imaging and Ramanspectroscopy are methods that can be used to investigate parts of the mechanisms. Toenable measurements at controlled oxygen concentrations a gas-tight microfluidic systemwas developed. In this thesis preparatory experiments to couple the gas-tight systemto a microscope that enabled simultaneous measurements with patch clamp, imagingand Raman spectroscopy are discussed. The patch clamp technique is to be used formeasurements on the dynamics of the ion-channels in the cellular membrane as well aschanges in membrane potential as a response to hypoxia. Imaging of PASMCs is requiredto successfully apply the patch clamp technique. Further, imaging will also reveal whetherthe mechanical response of HPV has been triggered, for this purpose image analysis forestimation of optical flow can be used. Raman spectroscopy enables measurements ofbiochemical changes in redox biomarkers, cytochrome c and NADH, of the mitochondrialelectron transport chain. This thesis shows that the gas-tight microfluidic system providesoptimal control of the oxygen content, in an experimantal setting where the patch clamptechnique can be applied. Raman measurements showed significantly larger variationsin spectra compared to an open fluidic system, which is the conventional approach.However, the results showed a need for improved Raman preprocessing. For this purposea Convolutional Neural Network (CNN) was trained using synthetic spectra that providedoptimal reconstruction of the Raman signal. Finally, simultaneous imaging and Ramanspectroscopy of red blood cells were performed in a home built microscope. The resultspave the way for measurements on PASMCs.

Authors

Joel Wahl

Luleå tekniska universitet; Strömningslära och experimentell mekanik
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Kerstin Ramser

Luleå tekniska universitet; Signaler och system; Luleå tekniska universitet; Strömningslära och experimentell mekanik
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Mikael Sjödahl

Luleå tekniska universitet; Strömningslära och experimentell mekanik
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Fredrik Nikolajeff

Luleå tekniska universitet; Strömningslära och experimentell mekanik; Luleå tekniska universitet; Medicinsk vetenskap
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