A filtration cell for a biological sample comprising: an outer housing having a first end, a second end, and a sidewall extending therebetween, the sidewall defining a first chamber; an inner housing having a first end, a second end, at least one aperture, at least one vertical or horizontal indentation terminating into the at least one aperture and disposed within a sidewall of the inner housing, the sidewall of the inner housing, defining a second chamber, the inner housing being disposed within the first chamber and rotatable with respect to the outer housing and the at least one aperture providing an opening into the second chamber; wherein at least a portion of the inner housing comprises a filtration membrane wherein the filtration membrane is disposed over the at least one aperture; and an opening into the first chamber or the second chamber connected to a pressure unit wherein the pressure unit regulates a trans-membrane pressure across the filtration membrane; the filtration cell further comprising at least one support region adjacent the at least one vertical or horizontal indentation for supporting at least a portion of the filtration membrane; wherein upon rotation of the inner housing with respect to the outer housing, the filtration membrane is adapted to allow a first portion of the biological sample to pass from the first chamber into the second chamber wherein the first portion is directed along the at least one vertical or horizontal indentation to the at least one aperture and directly into the second chamber defined by the inner housing through the at least one aperture and to restrain a second portion of the biological sample in the first chamber. an outer housing having a first end, a second end, and a sidewall extending therebetween, the sidewall defining a first chamber; an inner housing having a first end, a second end, at least one aperture, at least one vertical or horizontal indentation terminating into the at least one aperture and disposed within a sidewall of the inner housing, the sidewall of the inner housing, defining a second chamber, the inner housing being disposed within the first chamber and rotatable with respect to the outer housing and the at least one aperture providing an opening into the second chamber; wherein at least a portion of the inner housing comprises a filtration membrane wherein the filtration membrane is disposed over the at least one aperture; and an opening into the first chamber or the second chamber connected to a pressure unit wherein the pressure unit regulates a trans-membrane pressure across the filtration membrane; the filtration cell further comprising at least one support region adjacent the at least one vertical or horizontal indentation for supporting at least a portion of the filtration membrane; wherein upon rotation of the inner housing with respect to the outer housing, the filtration membrane is adapted to allow a first portion of the biological sample to pass from the first chamber into the second chamber wherein the first portion is directed along the at least one vertical or horizontal indentation to the at least one aperture and directly into the second chamber defined by the inner housing through the at least one aperture and to restrain a second portion of the biological sample in the first chamber.