**2.3. TLM for assisted reproductive technology and its promise for clinical medicine**

TLM is emerging as a promising clinical technique for selecting embryos for transplantation, although the discussion is still under way whether TLM may become an alternative to preimplantation genetic screening [271, 272]. The so-called morphokinetic analysis [273] by TLM is aimed to assess the number, development and quality (viability) of embryos by monitoring cleavage anomalies, multinucleation [274] or specific cell cycle kinetics [274, 275] and cleavage divisions [276], aneuploidy [277, 278], which is considered as a key causal factor of delays in embryonic development toward a blastocyte [278], and even chromosomal abnormalities [279]. Although more clinical research is required to finally prove that TLM can identify the best embryo for transfer and has an advantage over the conventional incubation of embryos [280], TLM is under consideration for patenting as a method for selecting embryos for implantation [281, 282]. TLM can also be used for sperm motility analysis [283].

One of the potential medical applications of TLM is the assessment of *ex vivo* engineered cells for cell therapy of degenerative and inherited disorders and other human pathologies like cancer [284–288]. TLM can also be used for diagnostics, for example, for detecting abnormalities in cell behavior in human dystrophic muscle cultures [289] or estimating tumor malignancy [290] in drug discovery [291], for testing gene therapeutic agents [292] and for evaluating side effects of antibiotics [293] and efficacy of chemotherapeutics [294, 295]. TLM is a valuable tool for understanding the pathogenesis of certain disorders, such as dysplastic erythroblast formation of erythroblasts from the patient with congenital dyserythropoietic anemia [296], thrombus formation [224], IgE-mediated mast cell degranulation and recovery [297], imaging of disease progression in deep brain areas using fluorescence microendoscopy [298], reprogramming in induced pluripotent cells [110] and other applications.
