The capabilities of an experimental setup combining the functions of a conventional microscope with a custom built self-mixing interferometer to characterize the contractile motion of living cells in both the transversal and longitudinal directions were explored. The use of discrete wavelets to denoise experimental signals combined with the application of a Hampel filter was shown to outperform standard denoising methods found in the self-mixing literature. Furthermore, an efficient iterative method to reliably estimate the optical feedback level and the linewidth enhancement factor was developed. Experimental displacements of microspheres, used as phantoms for living cells, were reconstructed with a resolution better than 0.15 lambda using the proposed reconstruction method. These results substantiate the claim that the proposed reconstruction method will enable the measurement of the contractile motion of individual cardiomyocytes with a resolution approaching 100 nm.