What are the mandatory layout requirements for the microbiology testing and physicochemical testing zones within a stem cell quality control laboratory?

I. Mandatory Cleanliness Classifications

Microbiological testing areas (sterility testing, microbial limits, mycoplasma testing) require a Grade C (Class 10,000) clean environment; Class A local laminar airflow must be maintained inside biosafety cabinets; independent airlocks and double-door interlocked pass-through boxes are required.

The positive control room must be a separate, enclosed compartment maintained under constant negative pressure (-8 to -15 Pa) with a dedicated exhaust system to prevent pathogenic bacterial aerosols from contaminating the broader QC area; it must not share a room with the general microbiology laboratory.

Physicochemical testing areas (pH, osmolality, impurity testing, reagent titration, spectroscopy) require a Grade D (Class 100,000) base environment; workstations handling strong acids, strong bases, or organic reagents must be equipped with independent fume hoods.

Critical Constraint: The sterility room, positive control room, and physicochemical testing room must not be combined into a single space; simple separation using only glass partitions is prohibited.

II. Mandatory Standards for Physical Barriers and Wall Construction

Complete enclosure using fire-resistant, solid cleanroom partition walls; all gaps in walls and ceilings must be sealed with sealant; direct interconnecting doorways between the two zones are prohibited; sample transfer must rely solely on double-door interlocked, sterilizable pass-through boxes.

The entire QC area must be separated from the stem cell preparation area by solid walls; ventilation ducts for the QC area must not be connected to the cleanroom system serving the cell preparation area.

Reagent storage rooms and temporary storage areas for hazardous waste/liquids must be located downwind of the physicochemical testing area, maintaining a straight-line distance of at least 12–20 meters from the microbiological cleanroom areas.

III. Mandatory Requirements for Pressure Differentials and Ventilation

Pressure differential gradient: Microbiological clean area > Buffer corridor > Physicochemical testing area; the microbiology room must maintain a positive pressure of +10 to +15 Pa relative to the outer corridor to prevent chemical vapors from the physicochemical area from infiltrating the aseptic workstations.

The two sets of cleanroom HVAC and exhaust ductwork must be completely independent; supply air and return air systems must not be interconnected. Exhaust from physicochemical fume hoods and organic waste gas must be vented separately to the outside at a high elevation; exhaust from the positive control room must pass through an H13 HEPA filter before discharge and must not be vented into indoor corridors or clean passageways.

IV. Separation Rules for Personnel, Material, and Waste Flows

Personnel Flow: Separate entry and exit routes are established for the microbiology QC and physicochemical laboratories; staff cannot pass directly from physicochemical rooms into the microbiology clean corridor; entry into the microbiology zone requires completing the full gowning sequence (primary change, secondary change, and airlock/buffer).

Sample Flow: Stem cell samples awaiting testing enter the microbiology sterility testing area first before being transferred to physicochemical testing stations; corrosive waste liquids and reagent residues from the physicochemical zone are strictly prohibited from flowing back into the microbiology clean zone.

Waste Flow: Separate transfer routes are established for infectious microbiological waste liquid and chemical waste liquid; the transfer of contaminated materials must not cross through the microbiology clean corridor at any point.

V. Airflow Direction and Layout

Alignment with Prevailing Wind: The microbiology clean zone is located upwind, while the physicochemical testing zone is located downwind; this prevents aerosols from volatile organic solvents from contaminating sterile workstations via the wind.

Flow cytometers and precision testing equipment are positioned on the microbiology side, away from corrosive gases (acids, alkalis, and organic solvents) originating in the physicochemical zone.

VI. Mandatory Requirements for Compartmentalization

Microbiology Zone (Must be separate rooms): Buffer airlock, positive control room, sterility testing room, microbiology incubation room, and sterilization/pre-treatment room.

Physicochemical Zone (Separate provisions): Explosion-proof reagent storage cabinet, gas cylinder compartment, ventilated workstation, and temporary storage compartment for physicochemical waste liquid.

Sinks, sterilization tools, and work uniforms for the two zones must be kept separate and dedicated to their respective areas; cross-zone usage is strictly prohibited.