There are few options to consider here. It is essential to keep support staff to a minimum. The point is that even in isolation a scientist may need some help, but no Evil Scientist is trying to run a major research lab.
Security is also a major concern.
Keeping tabs on a trusted henchman or a couple of automatons is one thing, managing a slew of underlings can become trying as they will invariable start demanding things like health care and pensions. Bearing this fact in mind any of the following can be used for that extra bit of support. In a modern lab these will almost certainly be a major component of the support staff. Various robots to handle sample retrieval, perform experiments and keep tabs on intruders are always welcome. Moreover, this is one case where numbers aren't necessarily a hindrance.