Disrupting the wall accumulation of human sperm cells by artificial corrugation

Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells $60 \mu m$ long, strongly confined to $25 \mu m$ shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine.Comment: 9 pages, latex. In accepted version on April 14, v2: abstract modified, information added to Sec. II.A and experiments added to Sec. III.A and Fig.3. Sec. III.C was deleted. Requested references adde

Geometrical guidance and trapping transition of human sperm cells

The guidance of human sperm cells under confinement in quasi-2D microchambers is investigated using a purely physical method to control their distribution. Transport property measurements and simulations are performed with diluted sperm populations, for which effects of geometrical guidance and concentration are studied in detail. In particular, a trapping transition at convex angular wall features is identified and analyzed. We also show that highly efficient microratchets can be fabricated by using curved asymmetric obstacles to take advantage of the spermatozoa specific swimming strategy.publishedVersionFil: Guidobaldi, Héctor Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Fil: Guidobaldi, Héctor Alejandro. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Biología Celular y Molecular; Argentina.Fil: Jeyaram, Y. Katholieke Universiteit Leuven. Institute for Nanoscale Physics and Chemistry; Bélgica.Fil: Berdakin, Ivan. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Berdakin, Ivan. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Moshchalkov, V. V. Katholieke Universiteit Leuven. Institute for Nanoscale Physics and Chemistry; Bélgica.Fil: Condat, Carlos Alberto. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Condat, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Marconi, Verónica Iris. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Marconi, Verónica Iris. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Giojalas, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Fil: Giojalas, Laura Cecilia. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Biología Celular y Molecular ; Argentina.Fil: Silhanek, Alejandro V. Université de Liège. Faculté des Sciences. Departement de Physique; Bélgica.Biofísic

Los espermatozoides que responden qumiotacticamente hacia la progesterona tienen el acrosoma intacto

Fil: Guidobald, H. A. Universidad Nacional de Córdoba. CBICEM; Argentina.Fil: Guidobald, H. A. Universidad Nacional de Córdoba. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Fil: Hirohashi, N. Oki Marine Biological Station, Shimane University; Japón.Fil: Giojalas, L. C. Universidad Nacional de Córdoba. CBICEM; Argentina.Fil: Giojalas, L. C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Para fecundar el ovocito, los espermatozoides de mamífero llevan a cabo la capacitación espermática. Este proceso involucra, entre otros, la adquisición de la habilidad para realizar la reacción acrosómica y la respuesta quimiotáctica. La quimiotaxis es un mecanismo que puede ayudar al espermatozoide a encontrar al ovocito, mientras que la reacción acrosómica facilita el paso del espermatozoide a través de las envolturas del ovocito.Fil: Guidobald, H. A. Universidad Nacional de Córdoba. CBICEM; Argentina.Fil: Guidobald, H. A. Universidad Nacional de Córdoba. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Fil: Hirohashi, N. Oki Marine Biological Station, Shimane University; Japón.Fil: Giojalas, L. C. Universidad Nacional de Córdoba. CBICEM; Argentina.Fil: Giojalas, L. C. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina.Biología Celular, Microbiologí

Sperm chemorepulsion, a supplementary mechanism to regulate fertilization

Are human spermatozoa able of chemorepulsive behaviour? Capacitated human spermatozoa are able to be chemorepelled by synthetic Progesterone Receptor Ligands (sPRL, known as contraceptives) and zinc (a cation released by the oocyte upon fertilization). Moving cells can be oriented towards or against a molecular gradient, processes called chemoattraction and chemorepulsion, respectively, which have been described in unicellular organisms such as amoebas and bacteria, to organismic cells such macrophages and developmental cells. In the case of spermatozoa, chemoattraction may help the finding of an oocyte and has been widely studied in various invertebrate and mammalian species; however, chemorepulsion has not yet been verified in spermatozoa. This is an in vitro study involving human, rabbit and mouse spermatozoa which were used to perform 3-30 experiments per treatment. Human sperm samples were obtained by masturbation from healthy donors who gave written consent. Only those samples exhibiting normal semen parameters according to current WHO criteria were included in the study. Rabbit spermatozoa were obtained by artificial vagina whereas mice spermatozoa were obtained from epididymis. The sperm selection assay (SSA), originally designed to evaluate sperm chemoattraction towards progesterone (P), and a video-microscopy and computer motion analysis system were used to test sperm chemorepulsion. Additional kinetic parameters were also determined by video-microscopy and computer motion analysis. In some experiments, the level of induced acrosome-reacted spermatozoa was determined. Rabbit mating manipulation was achieved to perform the sperm-oocyte co-incubation assay. Sperm accumulation in the well containing 100 pg/ml of sPRL was lower than the culture medium negative control (P < 0.05). The percentage of sperm persistence against the well containing 100 pg/ml ulipristal acetate (UPA) (P = 0.001), and the percentage of sperm showing a repulsive pattern of movement (a linear trajectory followed by a transitional one after turning against the UPA), were higher than the culture medium negative control (P = 0.049). Sperm accumulation was diminished when spermatozoa where exposed to a homogeneous distribution of 100 pg/ml sPRL combined with a chemotactic gradient of progesterone (P), with respect to the culture medium negative control (P < 0.05). These results were reverted when non-capacitated spermatozoa were used to perform the same experimental settings. The accumulation of spermatozoa against 100 pg/ml sPRL was lower than the culture medium negative control also in rabbits and mice (P < 0.05). The relative number of rabbit spermatozoa arriving to the vicinity of the oocyte was diminished under the presence of 100 pg/ml UPA (P = 0.004). Sperm accumulation in the well containing zinc was decreased compared to the culture medium negative control (P < 0.05). A homogeneous distribution of zinc combined with a gradient of 10 pM P, was lower than the culture medium negative control (P = 0.016). The results were quite reproducible with two different methodologies (accumulation assay and video-microscopy combined with computer motion analysis), in three mammalian species. The experiments were performed in vitro. Even though a quite complete characterization of sperm chemorepulsion was provided, the molecular mechanism that governs sperm repulsion is currently under investigation. Since the chemorepelled spermatozoa are those physiologically ready to fertilize the oocyte, these findings may have both biological and clinical implications, preventing either polyspermy under natural conditions or fertilization under pharmacological treatment with sPRL32815601573Universidad Nacional de Cordoba (Argentina) PCC-UN

Sperm physiology varies according to ultradian and infradian rhythms

Abstract The spermatozoon must be physiologically prepared to fertilize the egg, process called capacitation. Human sperm samples are heterogeneous in their ability to capacitate themselves, which leads to variability between samples from the same or different donors, and even along the seasons. Here we studied sperm variation in the capacitation state according to the ability of capacitated spermatozoa to acrosome react upon stimulation (% ARi) and to be recruited by chemotaxis (% Chex). Both indirect indicators of sperm capacitation increased along the incubation time with fluctuations. Those capacitated sperm recruited by chemotaxis showed an ultradian rhythm with a cycle every 2 h, which might be influenced by unknown intrinsic sperm factors. Two infradian rhythms of 12 months for the % ARi and of 6 months for % Chex were observed, which are associated with the joint action of temperature and photoperiod. Thus, to avoid false negative results, human sperm samples are recommended to be incubated for a long period (e.g. 18 h) preferably in spring time. This innovative point of view would lead to better comprehend human reproductive biology and to think experimental designs in the light of sperm cyclicity or to improve sperm aptitude for clinical purposes