what kind of current sense amplifier is suitable for OTP cells?
programmed cell = 10uA
unprogrammed cell = 50nA
any recommendation on the architecture ?
The architecture depends entirely on the critical specs of the design. Are you optimizing for speed, power, voltage, or area? Is there temperature sensitivity or variation of the cell current?
One good starting point is the common gate amplifier included in attachment. It's a workhorse for nonvolatile memories. If you post other critical design issues, this can be modified to fit them or may require a new method.