The conference CellTiss Days 2019 focuses on physical studies of biological processes from the molecular to the cellular and tissular scales. It will take place in the South of France, at "Belambra Club Les Criques" located near the peninsula of Giens, from 5 to 7 November, 2019. This conference echoes the GDR "Celltiss" which, over the past 12 years, has brought together a broad community of scientists addressing fundamental biology issues from an interdisciplinary perspective. We plan to use CellTiss Days as a springboard to create a new GDR entitled "Quantitative Approaches to Life", which will explore new horizons at the interface between physics and biology. The present conference will encompass five broad topics: molecular assembly and dynamics, cell and tissue mechanics, signalling-regulation-networks-systems, collective phenomena, optical methods - focus on new technologies. We hope to attract a large number of young researchers who will be encouraged to take advantage of the poster sessions and many slots set aside for contributed talks.